4AC / 4AGE Race motor advice please.

sneaky pete
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4AC / 4AGE Race motor advice please.

Postby sneaky pete » Wed Apr 12, 2017 11:01 pm

Howzit all. I joined the forum in the hope that I can get some help and guidance on building a race motor here.

No multivalve motors allowed - only 8V SOHC 1600cc. So I know you can put a 4AGE on a 4AC so why not the other way round? I appreciate we will have to get the head gas flowed properly. It is a 15 to 16 second circular track (2nd gear - W58), locked diff. So judging by other cars they rev from +- 4000 to 8500 RPM.

Fuel injection with racing fuel 16:1 CR (would you recommend 4A-EL then? what are valves & ports like?), headers (make our own), would you suggest 20V? stronger? we would pocket pistons, lighten flywheel, balance motor, racing clutch.

I have seen comment on the 4AGE oil pumps not liking high RPM. Some tracks are longer so we might go over 8500 RPM. Some one posted a 1G oil pump?
Can one get roller rockers for the 4AC?

Input from members would be appreciated.

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jondee86
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Re: 4AC / 4AGE Race motor advice please.

Postby jondee86 » Thu Apr 13, 2017 2:50 pm

Just to be clear.... you are talking about fitting a 4AC head on a 4AG block... yes ?

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sneaky pete
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Re: 4AC / 4AGE Race motor advice please.

Postby sneaky pete » Fri Apr 14, 2017 6:19 am

Thanks for the reply jondee86. Yes that is correct.
I have been doing some research. This is going to be a costly exercise - thus seeking advice / comments.

Evidently all 4A heads and blocks are of the same bolt pattern / interchangeable. Some have fitted 4AGE heads on 4AC blocks evidently no problem - they virtually bolt straight on. Cam belts and tensioners and covers are said to be a bit of a fiddle. Although this can be evidently be done, the general advice is to go with the stronger bottom end of a 4AGE - ie fit a complete 4AGE rather.

Now for us to suit the race rules and regs (which stipulate an 8V SOHC head, non race pistons (may be pocketed) plus std rods) we want to fit a 4AC head seriously flowed / ported with special cam on a 4AGE bottom end. Would the 16V or 20V bottom end be better?

Is there an issue with 4AGE oil pumps at high RPM and if so how do you overcome it? My son and I are very excited and cannot wait to hear what you guys think. We will keep the forum posted plus pics.

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oldeskewltoy
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Re: 4AC / 4AGE Race motor advice please.

Postby oldeskewltoy » Fri Apr 14, 2017 10:15 am

You will want custom pistons, the 4AC chamber is smaller, and the valve arrangement may cause issues with 4AGE pistons.

As to oiling... the Toda oil pump gears should work as long as you use the 4AGE oil pump.

I don't know anyone currently making 4A SOHC camshafts, but you can likely get one made
OST Cyl head porting, - viewtopic.php?f=22&t=300

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Re: 4AC / 4AGE Race motor advice please.

Postby jinx » Fri Apr 14, 2017 5:23 pm

why the heavier W58 ? 4AC probably wont make enough torque to stress a t50.

where will u find an injected 4A ? A week ago i stumbled on a picture of a 4A-E on the web. Never seen one before. I'd love to get my paws on one, and blow some boost thru these last 2 or 3 4AC I know of... and see how they like it
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some members ran delta cam in their 4AC. Delta seem to know what they're doing as their DSM cams cost less & still perform on par

the Iskenderian cam in my 3tc pressed u in the seat from ~3700 to 8500rpm. No other cam I tried came close. Twin sidedraft carbs.
I only added valvesprings. Call Isky n c what they say

i suppose boost not allowed ? Stock 4AC perform surprisingly well with simple draw thru small turbo. Can smoke a cammed up 4AG
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sneaky pete
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Re: 4AC / 4AGE Race motor advice please.

Postby sneaky pete » Sun Apr 16, 2017 1:24 am

Thanks again guys. Yes I appreciate the head and pistons will need work plus to get it to 16:1 CR.
We chose the W58 over the T50 because of the faster 2nd gear ratio which we run in when racing. We do not have a very good selection of axle ratios here. I do hear you on the weight though and that is always something we could change (back to T50) without too much of an issue. The fuel injected motors are Japanese imports.