Carbed 4AG results - 152 whp

[Evochile]

Spec list:
- Wiseco high compression pistons
- Stock rods with ARP bolts
- HKS 272 cams, stock valvetrain
- Stock crank
- Midly ported bigport head
- Weber DCOE 45
- "TRD-like" exhaust manifold



Sorry for not showing the full run, we were testing cam gear position and jetting, we just need the 5000rpms+ powerband with current gearing.







The car is also pretty light

[oldeskewltoy]

Nice!

assume with those fluctuating AFRs, there might be a few more ponies in there as well.

Are the Wiseco's "off the shelf", or something you had made? Would love to know more about the headwork as well.

[Evochile]

Yes, first dyno test, still need to improve on a few areas: A/F is one, the other is that the car is running fixed advance (it does have a primitive MSD retard, but this is far from optimal).

Off the shelf Wisecos. Nothing too fancy. Regarding headwork, it is fairly minimal, just removed castings, 3 angle valve job, and a very light porting. Having no flow bench at hand, it is far easier to destroy a head rather than improve on it.

Builder is confident that it can rev to 8300rpms for a long time. I have my doubts on the stock crank and stock oiling system. We will see. After four races we will open up the motor and see how it is holding up.

[Deuce Cam]

Looks good. What's the static compression on the pistons, and total ignition timing set at? Can the stock valve train handle 8k+ rpm?

[Evochile]

Final static compression is 13.0:1 Timing is 32° from 3000rpms onwards (as I said, primitive timing control).

As for the stock valvetrain handling 8k+, stock redline on the JDM engine was 7700rpms IIRC, so 8.300 rpms (current rev limit) should be possible with appropiate valve springs and correct balancing. We will see. So far it has seen about 8 hours of operation and it is still running strong. Any abnormal wear should show up on engine disassembly in a few months.

[dr.occa]

Very nice numbers. 12.75 is actually a pretty nice ballpark for a carb'd 4AGE to play in comfortably.

[allencr]

Please list your jet sizes, also the main & aux. venturies(sp).
Thank you.

[carbd7age]

Wow.

[Crownvicman289]

You're just scared of ventilating the block at high RPMs then? Because to my knowledge those 272s have a bit more room to rev and the dyno sheet proves that. Do you road race or drift?

[Evochile]

Allen, venturis are 36mm, will try 32 on the next dyno session. Rest of the sizes only the builder knows, I can find that out if you need it.

Crown, yes, I´m not sure the stock crank and oiling system are up to par for frequent visits to the 8.500+ rpms zone.
I road race the car. The car had it first race yesterday, held up with no problems.

[eightsixgts]

Please, if you don't mind.. find out from the tuner what jets you're running with your setup right now. Very curious.

Also, a smaller venturi is something you don't want to do unless you're trying to create a little more torque in the lower RPM range. 36mm is about right for those 272 cams, and I'm strongly considering bumping up to 38 or 40mm on my 304/288 cam setup.

[Evochile]

Sure, I will ask for fueling details, no problem.

At what RPMS is your cam setup making peak power?

[eightsixgts]

Unfortunately, I haven't schedule any dyno time yet. I've primarily done my tuning by the way of street and wideband. My butt dyno tells me the cams fall off mid-late 8k RPM. I should be getting on a chassis dyno here very soon, however. My setup is a little bit more mild than yours, with 11.8:1 compression, 304/288, largeport with de-burring and smoothing of ports, TODA valve springs etc, 3-angle valve job, Weber45s, LW flywheel, TRD headers etc.

I'm interested to see how your jet chart compares to mine. I've been compiling various charts from other people with varying setups and they've all been in the same general area, with a few exceptions.

[oldeskewltoy]

I'm interested to see how your jet chart compares to mine. I've been compiling various charts from other people with varying setups and they've all been in the same general area, with a few exceptions.

Please SHARE.........

[eightsixgts]

I'm interested to see how your jet chart compares to mine. I've been compiling various charts from other people with varying setups and they've all been in the same general area, with a few exceptions.

Please SHARE.........

I'll share it in the dedicated carb thread, I don't want to de-rail this guys thread too much

[Gt racer]

Dont be afraid to try the smaller chokes. In a road race car you are going to find that torque is as important if not more so than HP. You want to pull out of the turns as quickly as possible. Giving up a little at the end of the straight is better than lagging behind coming off of a slow turn. I Run a GTL car with a single inlet restrictor with fuel injection now. We found the smaller SIR's produced better torque and better HP up to 7000 +/- rpm's. At higher RPM's the HP of the larger choke was better but not by as much as you would think. Before we were restricted I ran twin 45mm Weber side drafts. When the SCCA made us run smaller chokes we actually went faster. I'm the same whp as you with a 120 #'s of torque running a 23.5mm SIR.

[dr.occa]

^ this is good advice depending on your course. 36+ chokes are for stretches that let you build up. Try also longer and custom stacks to regain overall power band torque. The closer to the 1st wave of reverberation tuning the better response.

A great working example of this is the real-time, variable slide stacks on the Le Mans R26B motor. This is at least the penultimate throttle solution for optimum torque throughout the entire powerband of any car. Don't ask me what the ultimate solution is...anyway...