Ideal intake length for stock 4AGE 16v bigport?

MKIndy4AGE
Posts: 7
Joined: Fri Jan 11, 2013 10:52 pm

Ideal intake length for stock 4AGE 16v bigport?

Postby MKIndy4AGE » Tue Sep 08, 2020 3:00 pm

Hi guys,

I'm hoping someone can help me figure out an intake issue. I'm building a Lotus 7 type car and am putting a stock 7 rib block big port 4AGE 16v in it. Im keeping it stock until the car is finished and road registered except that the limited engine bay space means the TVIS has had to go and i will be fitting ITBs onto a DCOE manifold and using a programmable ECU.

I'm trying to figure out the right intake length and all the calculators I've found online reckon it should be about 8.5 inches from the intake valve stem to the end of the ITB stack bellmouths for the stock 240 degree camshafts. If, as I intend to, once the car has been tested and road registered, I fit longer duration cams, the ideal induction length will get shorter according to the calculators.

Trouble is, with valve stem to side of head at just over 3 inches, the manifold at 2 inches thick and the throttle bodies at about 3.75 inches long, it's over 8.5 inches even before any stacks are fitted. Also, of the photos I've seen of tuned 4AGEs on ITBs, they all look much longer than 8.5 inches.

So, have I got it all wrong, or do I need to start looking for a shorter manifold and shorter ITBs? Can anyone help me?

Thanks

Pete

Disable adblock

This site is supported by ads and donations.
If you see this text you are blocking our ads.
Please consider a Donation to support the site.


User avatar
jondee86
Moderator
Posts: 2698
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby jondee86 » Tue Sep 08, 2020 8:38 pm

Here is an example of an on-line calculator from Wallace Racing...

Image
http://www.wallaceracing.com/intake-runner-length.php

This produces a range of answers produced by different empirical calculation methods.
For the purposes of generating an example I have entered up a reasonable approximation
(I hope :) ) of the kind of values you would be using. From this I would take 13" as being
a decent target length from valve head to end of bellmouth.

An alternative method is to use similar data to calculate the length at which the various
intake harmonics will create the strongest pressure wave at the intake valve at your
preferred rpm. There will be several harmonics that occur at different distances and
which become weaker as they get further from the valve head. The idea being to choose
the length that uses the strongest pressure wave at a usable length.

When I went thru this process it all got a bit complicated and I settled on 350mm (13.5")
as my target and managed to get close to that in the final setup. The thing to remember
is that the pressure wave is tuned to have maximum effect at a specific rpm, and the
"supercharging" effect tapers off either side of that rpm. So you need to choose the part
of your rpm range where you would like the benefit to be felt.

Image

As you have noted, the 350mm target length was sort of OK for stock cams (on a 10.3:1
comp engine), but with 272deg cams I found short bellmouths to work really well so the
ideal length for my engine was probably closer to 300mm (12").

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

MKIndy4AGE
Posts: 7
Joined: Fri Jan 11, 2013 10:52 pm

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby MKIndy4AGE » Tue Sep 08, 2020 11:12 pm

Thanks for the reply Jondee86, that's a great explanation and a calculator I have not seen in my searches. The length you calculated makes much more sense than the ones i was seeing. A few questions if you don't mind:

1. Not that it makes a huge difference, but I thought peak power on stock bigport cams is at 6600 rpm?
2. Presumably the "Desired RPM" entry is, as you say, the part of the rpm range where I want to make peak power? I've not driven a car with an engine that revs as high as a 4AGE and will be using my very light (about 500-600 kg) self-built car for fast road driving and track days, so what peak power revs would you suggest?
3. Being a fairly unique installation, I'm going to have to get a custom exhaust made. Is there an exhaust calculator you'd recommend?
4. You mention that you have 272 degree cams in your 4AGE. I have a pair of HIS 272 degree, 8.1mm lift cams I'm going to put in the engine once the car is registered and was wondering how they might behave i.e. how smooth is the idle with yours, whats the power range and what rpm do you make peak power, how much power and what other mods youve made i.e. compression, porting etc?

Sorry about all the questions but it's great to hear from someone who seems to really know their stuff and has the set up I'm looking to end up with.

Thanks again Jondee86!

User avatar
jondee86
Moderator
Posts: 2698
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby jondee86 » Wed Sep 09, 2020 1:02 am

1. I just picked those rpm numbers out of the air to get the calculator to make a demo.
This.... http://club4ag.com/technical_main.htm seems to suggest 6600 and 5200 rpm
for max power and torque on stock engines The stock engine tops out at 6600 and then
dies. So while it will run to 7800 on the factory ECU there is not much point in pushing
past 7000 as you would be better off taking a taller gear.
2. The 4AGE 16V loves to rev and if you targetted 6000 rpm you would get some benefits
in the 5000 to 7000 rpm range which is you will be working if you want to get the best out
of the engine with stock cams and compression.
3. I used the factory cast iron RWD exhaust manifold and 2 into 1 section with a 2" custom
exhaust. For a road car my aims were a bit different... I was looking to maintain and
optimise torque on the little engine rather than hit maximum power. Maybe Wallace
Racing have a calculator ?
4. I used a stock late model "smallport" engine from a low mileage from a wrecked FWD
Jap import. The engine was never opened and mods were basically all bolt-ons. Custom
ITB tube manifold with Silvertop ITB's and custom bellmouths. Aftermarket ECU running
wasted spark ignition (GZE coilpacks, GZE CAS, Subaru igniter), Silvertop ISCV, lightened
stock flywheel and a set of 272/268 duration 8.5/8.2 lift cams.

Self-tuned and ran pretty well. Idled with a little bit of a lope but nothing special, pulled
smoothly from as low as 1500 rpm if you were gentle on the throttle and ran hard from
3500ish to 7000 plus. I had it redlined at 8200 and it went there regularly :)

Image

These graphs look a bit different from the normal rolling road type as they were made
by a Dynapack hub dyno that shows actual instantaneous torque rather than the heavily
smoothed curves produced by the roller inertia of the rolling road. The torque flucuations
are not really noticeable in the car due the the inertial mass of the car on the road.
I believe it is intake and exhaust resonances that cause most of the waves :)

https://www.youtube.com/watch?v=4MSwjxtLPLE

Be aware that you will need more compression to get the best out of your HKS cams as
they are biased a little more to making power at high revs rather than lower in the power
band. You will also need adjustable cams wheels to set the best cam timing.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

Disable adblock

This site is supported by ads and donations.
If you see this text you are blocking our ads.
Please consider a Donation to support the site.


davew7
Club4AG Expert
Posts: 200
Joined: Fri Jun 06, 2014 4:34 am
Location: Michigan

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby davew7 » Wed Sep 09, 2020 4:30 am

An exhaust option is the 20V exhaust header. You would have to cut them just be low the 2 into 4 merge point, and do a 90* turn out the engine bay. You may also have to route the steering shaft around the exhaust. I would go with Jondee86 suggestion, even with a stock big port and up the compression ratio. It will not be an issue with that light wt of a car.
Davew7

User avatar
oldeskewltoy
Club4AG MASTER
Posts: 2053
Joined: Wed Jan 09, 2013 4:44 pm
Location: Portland, Oregon

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby oldeskewltoy » Wed Sep 09, 2020 7:04 am

MKIndy4AGE wrote:4. You mention that you have 272 degree cams in your 4AGE. I have a pair of HIS 272 degree, 8.1mm lift cams I'm going to put in the engine once the car is registered and was wondering how they might behave i.e. how smooth is the idle with yours, whats the power range and what rpm do you make peak power, how much power and what other mods youve made i.e. compression, porting etc?


intake cam card...

Image


exhaust cam card

Image


HKS 272 cams are designed to twist up to 8800 rpm. I would also advise at least 11:1 compression ratio for that long of a duration camshaft. With proper tuning the idle will have a small lope, and it will likely need to idle a bit over 1000 rpm. As to porting, with such mild lift levels it isn't required, but power = air flow, so a proper port job will unleash more power. If you don't want to open up your engine, may I recommend a set of Cat cams... they are mild cams(duration) with nearly the same lift as the HKS

Image
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

MKIndy4AGE
Posts: 7
Joined: Fri Jan 11, 2013 10:52 pm

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby MKIndy4AGE » Wed Sep 09, 2020 10:20 am

Thanks for your reply Oldeskewltoy. I asked the question because, having bought these cams I'm growing a little concerned that they at be too extreme for the kind of driving I want to do i.e. fast road driving and on track days. I don't want a race engine and, while I want to boost the torque power of the stock engine, I do want an engine that is going to idle fairly smoothly and be something I can drive in traffic. I don't mind opening the engine up and doing a bit of porting and upping the compression. I'm an engineer, admittedly mainly on submarines, so this sort of work does not bother me.

The thing is, I'd rather sell my cams on while they are unused and buy something more suitable if they are not going to give me the end result I'm after. So, if I'm looking to get about 150hp out of my engine but still retain drivability, what would you recommend I do with cams, compression etc. Also, whats the best way to achieve that boost in compression, skimming, pistons?

Thanks

Pete

User avatar
jondee86
Moderator
Posts: 2698
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby jondee86 » Wed Sep 09, 2020 3:32 pm

For a 1600cc street engine capable of track day fun, lift is more beneficial than duration.
If you research "rally" cams you will find that they trade off ultimate high rpm power for
more "grunt" at lower rpm's to help the cars accelerate out of corners. They do this by
increasing the lift over stock with just a mild increase in duration. Of course this wisdom
only applies to old school NA rally cars, not the "all day on the limiter" turbocharged 4WD
rocket ships of the WRC today.

On my car I found maximum power at 7200 rpm with a pair of used cams of unknown
origin. Peak torque was at 6000 rpm. This meant that the engine speed range for having
fun was from 5000 to 7500 rpm. Having a cam that will run to 8800 rpm does not mean
that it makes peak power at 8800 rpm. Peak toque and power will occur earlier but the
engine will still be making usable power until 8800 rpm.

There are a lot of upgrade cams around, and one set that you might like to consider is
the Kelford 193-A "fast street cam" with 266/262 Degrees advertised duration and
8.59mm/8.20mm lift. You will be disappointed with mild cams featuring more duration
without a decent increase in lift... I was :( Butt dyno did not register any improvement

Cams are only part of the equation. If you want your engine to idle nicely and be pleasant
to drive in traffic, you need to keep intake velocity up by not oversizing the intake or
exhaust systems. More compression is always good but for 11:1 you will want to tidy up
the combustion chambers. Oldeskewltoy has a handle on how to build a sturdy 4AGE :)
He can tell you what CR you can get with a cut off the head and a 0.80mm MLS gasket.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

MKIndy4AGE
Posts: 7
Joined: Fri Jan 11, 2013 10:52 pm

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby MKIndy4AGE » Thu Sep 10, 2020 7:23 am

Hi Jondee86,

Thanks for all that. Realising now that when I bought those cams, during a business trip to the US several years ago because they are so much cheaper than in the UK, I was focusing too much on duration and not enough on lift. As you say, its about making more power while still having an engine that can be driven on the roads without having to keep it at 7-9k rpm all the time. Ironic really because a lot of people in the UK are putting superbike engines in these cars but they are not very "streetable" and I decided not to fit one for that reason. The 4AGE seemed to be the best compromise.

So, some cams in the region of 255-265 duration with 8-9mm of lift, mindful of the lift limit for the stock shims. Regarding intake I know I would probably have been better off getting a small port engine but couldn't find one for sale at the time, so presumably its about making sure the ITBs aren't too big. I was recommended 42mm ITBs by Omex in the UK; sound about right? I've also been looking at exhausts and, for street use I understand that a 4-2-1 system is preferable to a 4-1 system and opinion seems to be either 2" or 2 1/4" pipe from collector to the silencer/muffler. From what you say, it sounds as though 2" might be best.

As far as head work is concerned, from what I've read not a huge amount is required and I'd be happy to tackle that myself. I'd certainly be interested to hear what the best way to increase the compression ratio is, particularly if an appropriate increase can be made without resorting to changing the pistons, from a cost point of view.

Thanks again Jondee86

User avatar
oldeskewltoy
Club4AG MASTER
Posts: 2053
Joined: Wed Jan 09, 2013 4:44 pm
Location: Portland, Oregon

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby oldeskewltoy » Thu Sep 10, 2020 10:13 am

raising the compression in a 4AG pretty much requires $$ being spent. You will either need new pistons, or a set of adjustable timing pulleys, I'd actually recommend both.

** - One thing - there are 2 different rod/crank combinations that were in largeport 4AGEs. 1984 - mid 1987 3 rib blocks, got "small" cranks(40mm rod journals) those engines used a 18mm wrist pin. mid 1987 on, got "big" cranks(42mm rod journal), and they use 20mm wrist pins. After 30 years... either combination could be in your engine......

early crank/rods are much lighter, and as long as you keep rpm levels under 8500, it will hold up fine. One problem is 18mm wrist pin restricts low cost piston options. Molnar Technologies has a special rod available (about $420)that fits early crank, and yet uses far more common 20mm wrist pin.

ASSUMING you have a later crank: As far as pistons are concerned you can get away with buying aftermarket OEM smallport pistons, and rings. DNJ P927.20 (1/2mm oversize), and matching rings PR926.20 (again 1/2mm oversize) cost is about $300 or less for both. These will give you 10.3:1 pistons.

You could in theory mill the head as much as .030" reducing chamber volume from 36cc to about 33cc, that will bump compression to nearly 10:1. This method will require adjustable timing pulleys to correct for the amount of material removed. Additionally you may have now made the engine an interference engine, instead of it being none interference

As far as port work is concerned, there are a few areas that could use attention: 1) bowl/seat, for the build level you are after you want the bowl seat diameter to be 85% of the intake valves diameter (25.9mm). Once the bowl/seat is set, blend in the rest of the bowl. You don't need to do more on the intake side. 2) the exhaust side of the head is restrictive, ideally you set the bowl/seats to 86% (21.9), and then work the bowls, and the ports. There is a LOT of meat inside the exhaust ports - when I do the exhaust side, I typically change the port from a "Y" shape, to more of a "V" shape. Finally, 3) you are trying to deshroud the chambers removing/minimizing the machining marks on either side of the valves - be conservative doing this... ideally you add less then 1cc to the chamber. Each .010" cut is about 1cc removed -

my photos - they should give you some ideas - https://gallery.ostportworks.com/index.php

Adding a "lot" of lift, while not adding a lot of duration gets tough on valve springs - I'd recommend a set of Toda springs. As far as cams MANY companies have offerings, and many will say "drop-in", but I'd recommend getting a set of adjustable timing pulleys to properly set the cams.

since you are in Europe these guys have a lot to make building your 4AGE easier - https://flos.ie/
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

User avatar
oldeskewltoy
Club4AG MASTER
Posts: 2053
Joined: Wed Jan 09, 2013 4:44 pm
Location: Portland, Oregon

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby oldeskewltoy » Thu Sep 10, 2020 11:13 am

jondee86 wrote:Here is an example of an on-line calculator from Wallace Racing...

Image
http://www.wallaceracing.com/intake-runner-length.php


For the purposes of generating an example I have entered up a reasonable approximation
(I hope :) ) of the kind of values you would be using. From this I would take 13" as being
a decent target length from valve head to end of bellmouth.


A few issues/questions.... 1) intake closing would not be 240, it would be in the area of 47-70 - they are talking about ABDC. 2) stroke for 77mm would be 3.15".

Image

Stock cams peak @ 6600, and the peak torque would be 4800.

Where did you come up with runner volume??
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

User avatar
jondee86
Moderator
Posts: 2698
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby jondee86 » Thu Sep 10, 2020 4:29 pm

jondee86 wrote:1. I just picked those rpm numbers out of the air to get the calculator to make a demo.

Basically I just put numbers in all the boxes to get the calculator to produce an output. They
were a mashup of figures for stock and 272 cams plus a few guesses :) I did wonder about
the valve closing number and since it didn't specify, I went with ATDC. For intake runner
CSA I went with 42mm ITB size. The "Intake Plenum Volume" is a bit of a mystery. Looks to
be in the expected order of runner volume, although I understand plenum to be the "tank"
that the bellmouths connect into.

Back in the real world calculating the correct runner length is a bit of a crap shoot. The
ram effect produced by intake resonance calculations peaks at one specific rpm and then
only when the throttles are wide open. Either side of that rpm the beneficial effect fades
away. So yes, if you drive around at one particular (high) rpm with wide open throttles,
you will get some extra power. But driving like that on the street you will either kill yourself
or get arrested !!!

IMHO just get as much length as possible in your intake manifold and make the airflow
path smooth without sharp bends or rapid changes in section. Driving on the street or in
any kind of clubmans event requires an engine that is responsive at all rpm's and throttle
openings, and there are other and better ways of achieving that :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

User avatar
jondee86
Moderator
Posts: 2698
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby jondee86 » Thu Sep 10, 2020 6:42 pm

MKIndy4AGE wrote:So, some cams in the region of 255-265 duration with 8-9mm of lift, mindful of the lift limit for the stock shims.
Regarding intake I know I would probably have been better off getting a small port engine but couldn't find one
for sale at the time, so presumably its about making sure the ITBs aren't too big. I was recommended 42mm ITBs
by Omex in the UK; sound about right? I've also been looking at exhausts and, for street use I understand that a
4-2-1 system is preferable to a 4-1 system and opinion seems to be either 2" or 2 1/4" pipe from collector to the
silencer/muffler. From what you say, it sounds as though 2" might be best.

There is some useful information from Jenvey here... https://www.jenvey.co.uk/support/faqs/n ... t-in-nisi/
If I remember correctly, the 20V silvertop (AE101) ITB's that I used have a throttle plate diameter
of 43mm. This is larger than ideal for a responsive 16V engine, but they were readily available and
cheap :) At the time Jenvey recommended 38mm throttlebodies for the goals I had in mind. The
issue here is balancing intake restriction at WOT against the ability of the throttle to control the
engine correctly at smaller throttle openings. This is referred to as "control authority".

When the intake and throttle are sized for the maximum rpm WOT condition, as they can be for all
out circuit racing, the engine will suffer from poor performance at low throttle operation because
the intake velocity is too low to ensure proper mixture and cylinder filling. The early (bigport) 4AGE
engines were fitted with the TVIS system to help improve low rpm intake velocity. Oversized throttles
result in a loss of control authority as the intake manifold pressure will rise to atmospheric at a low
% throttle opening (my MAP was at atmospheric by 20% TPS). Thus opening the throttles past 20% had
no further effect on MAP rendering load setting by MAP ineffective. TPS had to be used for load setting
(fueling) and that system works very well.

So, long story short, I made some custom tapered "chokes" that effectively reduced the throttle size
to 40mm. Going down to 38mm would most likely have been better for autoX use, but 40 worked
fine on the street.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

User avatar
jondee86
Moderator
Posts: 2698
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby jondee86 » Fri Sep 11, 2020 2:58 pm

Feels more like this :D :D

Image

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

MKIndy4AGE
Posts: 7
Joined: Fri Jan 11, 2013 10:52 pm

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby MKIndy4AGE » Sat Sep 12, 2020 5:40 am

Thanks again for the replies guys.

Oldeskewltoy, my plan has always been to get some more power out of the engine once I finish the car build, as the emissions requirements will be very tight. Ironically, once it's registered, I think as a "vehicle of undetermined age" regular DOT test will require only a visible smoke test! I've been frustrated in building the car but have been buying up parts I thought I would need, so I already have HKS adjustable cam pulleys, a set of HKS uprated springs and a Cometic 0.8mm head gasket. Of course I thought I had the right set of cams but will be selling them on now. Should have asked you guys these questions a while ago!

I think I'd prefer to keep the engine non-interference, so will need to budget for a set of pistons when the time comes. I definitely have a 7 rib block, the engine came out of a Japan based Corolla, and AE92 I think, with red and black lettering on the car covers, so hopefully it has the later crank but I will check when I modify the sump for greaterground clearance.

The port work looks more involved than I was led to believe, so will think again about doing it myself. Your head work looks really good by the way!

Jondee86, it seems that about 13 inches will be what I'll need to go for. Oldskewltoy, do you agree with Jondee86 on that?. It looks like I'm going to need a different manifold though, as there is not enough space to fit that length in in my rather small Lotus 7 lookalike. I'm going to need a manifold that Anglesey throttle bodies up by 15-20 degrees, so that they will clear the side chassis rail. Im going to be using Jenvey or Omex ITBs, so will make sure i go for 40mm bore.
Thanks again

Pete

User avatar
jondee86
Moderator
Posts: 2698
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby jondee86 » Sat Sep 12, 2020 10:12 pm

If you aren't stuck og OMEX or Jenvey throttle bodies, these guys might be able to
sort you out... https://www.facebook.com/WhitleyTune/?rc=p

Image

Image

As far as I know the 1G is basically a 6-cylinder version of the 4AGE so the manifold
should not be a problem to Whitleytune. If you stay with the DCOE style throttlebodies
I think you will be up for a custom manifold anyway, as from what I have seen DOCE
to 4AGE manifolds are all built horizontal for carb use.

Anyway, got to promote NZ made when the chance comes up :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

MKIndy4AGE
Posts: 7
Joined: Fri Jan 11, 2013 10:52 pm

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby MKIndy4AGE » Mon Sep 14, 2020 7:57 am

Those ITBs look great Jondee86 but I think I'd be more comfortable not sourcing mine from the opposite side of the world, in case I have any issues. Omex is 18 miles from where I live and Jenvey 40 miles, so I know it will be easy to get help/parts from them should I need it. Don't blame you promoting NZ though. I have a friend who lives on Waiheke Island off Auckland and I took a 3 week vacation out there in 2014, seeing her and also spent a week touring south island. Loved it!

I think you're right about the manifold, there aren't any for DCOEs that are angled, because of course DCOEs need a horizontal float chamber. I have found a company, run by a guy who I first heard of on a build forum for my type of car, who make manifolds to order (https://danstengineering.co.uk/Manifolds-and-Plates/Jenvey,-Weber-and-Dellorto-Manifolds?page=4). They make an angled manifold for Jenvey SF ITBs, so hopefully will make me one for the DCOE ITBs. They are all made to order, so hopefully it wont cost too much.

Thanks again for all the advice.

Pete

User avatar
jondee86
Moderator
Posts: 2698
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby jondee86 » Thu Sep 17, 2020 6:49 pm

Got a bit of time today so I thought I would try the calculator again...

Image

Corrected a few errors and amended the figures to something more representative
of the cams that you might end up with. Didn't really have much effect on the length
calculated by the program. So I am inclined to think that the length is probably less
important than making sure that the airflow path is as smooth as possible.

Make the curved part with the largest radius you can fit, no abrupt changes of section
or steps. Port match to throttle bodies and head. Use a thermal gasket between the
manifold and the head... PTFE is best but other insulating materials will work.

Those DANs manifolds look good and they obviously know all about throttle bodies
so you should get a decent result if you go with them. Good luck :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

mr2mk1hero
Club4AG Enthusiast
Posts: 137
Joined: Mon Jan 26, 2015 2:40 am

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby mr2mk1hero » Fri Sep 18, 2020 11:36 pm

jondee86 wrote:Feels more like this :D :D

Image

Cheers... jondee86


:lol: :lol: :lol: :lol: :lol:
Check out my YouTube channel: https://www.youtube.com/channel/UCwosUn ... xtqkNJ3Fbg
Check out my blog: http://www.driving4answers.com/
Heaps of 4A-GE and MR2 mk1 aw11 content on both.

User avatar
oldeskewltoy
Club4AG MASTER
Posts: 2053
Joined: Wed Jan 09, 2013 4:44 pm
Location: Portland, Oregon

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby oldeskewltoy » Sun Sep 20, 2020 10:33 am

jondee86 wrote:
Corrected a few errors and amended the figures to something more representative
of the cams that you might end up with. Didn't really have much effect on the length
calculated by the program.
So I am inclined to think that the length is probably less
important than making sure that the airflow path is as smooth as possible.


This is why I often recommend the TecArt ITB adapter

Image

With proper port work the roof of the port continues a gentle downward angle to the bowl, and then around to the valve. the downside - smallport only, and for best effect - big valves.


If I may interject... All of these things don't make horsepower, they do help release some, but a properly built 4AG will make plenty of power.

For example a piston change, portwork to fit the application, and careful attention to detail during assembly... and 120+ whp later, along with torque very close to a Blacktops.....

Image


Stock intake, stock cams, stock exhaust, stock engine management. If you are more of a specs person.....

Image


Build it with enough power to begin with, and if you can better optimize, all the better, but don't expect to find horsepower when with some attention you can build it in.
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

MKIndy4AGE
Posts: 7
Joined: Fri Jan 11, 2013 10:52 pm

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby MKIndy4AGE » Wed Sep 23, 2020 1:41 am

Thanks again Jondee86 and Oldeskewltoy. So, as i said in an earlier post, I need to keep the engine stock until the car has passed the individual vehicle approval test I have to put it through here in the UK. Due to the unique design of the car, on the exhaust side, i will have to fit a custom 4-2-1 header, and have a cat in the exhaust to meet emission regs. On the intake side, custom manifold and ITBs. I also have an Omex 600 programmable ECU. Once its on the road, i want to increase the power without sacrificing too much low down torque (it is a very light car however, probably only 550kg).

From what you are saying Oldeskewltoy, the best route to this is new pistons/head skim to raise the CR to about 10.5:1, some head porting/ matching to headers and new cams of no more than 255 deg duration but increasing lift to about 8mm. Have I got that right?

Thanks

Pete

User avatar
oldeskewltoy
Club4AG MASTER
Posts: 2053
Joined: Wed Jan 09, 2013 4:44 pm
Location: Portland, Oregon

Re: Ideal intake length for stock 4AGE 16v bigport?

Postby oldeskewltoy » Wed Sep 23, 2020 8:21 am

MKIndy4AGE wrote:Thanks again Jondee86 and Oldeskewltoy. So, as i said in an earlier post, I need to keep the engine stock until the car has passed the individual vehicle approval test I have to put it through here in the UK. Due to the unique design of the car, on the exhaust side, i will have to fit a custom 4-2-1 header, and have a cat in the exhaust to meet emission regs. On the intake side, custom manifold and ITBs. I also have an Omex 600 programmable ECU. Once its on the road, i want to increase the power without sacrificing too much low down torque (it is a very light car however, probably only 550kg).

From what you are saying Oldeskewltoy, the best route to this is new pistons/head skim to raise the CR to about 10.5:1, some head porting/ matching to headers and new cams of no more than 255 deg duration but increasing lift to about 8mm. Have I got that right?

Thanks

Pete


Essentially... yes. There are more specifics to follow, but more power = more airflow. As you are in the Uk, you might want to look up Richard Macer - he builds a LOT of 4AG engines.

As far as "stock" goes, the engine in the dyno(120+whp) above is essentially stock - with some minor tweaks - it did pass the current owners states emissions tests.
OST Cyl head porting, - viewtopic.php?f=22&t=300

Building a great engine takes knowing the end... before you begin :ugeek:

Enjoy Life... its the only one you get!

Disable adblock

This site is supported by ads and donations.
If you see this text you are blocking our ads.
Please consider a Donation to support the site.



Return to “TECH: 4A-GE ENGINE”

Who is online

Users browsing this forum: No registered users and 7 guests