GTRA 302 Windsor Dyno Results

[NZGTRA17]

Having finally pieced together an interim engine based around the shortblock received with the car we got it onto the dyno yesterday.

Basics of engine are; 224/232 @ .050" lift Comp Cams Hyd Roller Cam, std Ford Motorsport Hyd roller lifters, 1.6 ratio Comp roller rockers, pistons notched to accomodate 2.02" valves (easy job using Isky notching tool), Brodix CNC 185 cc intake runner heads, port matched Edelbrock RPM Airgap manifold with 1" open spacer, Demon 650 cfm General Competition carb (72 / 79 jets), Pipercross foam air cleaner, Procomp HEI dist, approx 9.5 comp ratio, std Panoz GTRA shorty headers & exhaust. All runs conducted with ignition timing of 34 degs 'all in'.

Dyno results; dynoing was done on a Dynojet dyno (common unit in the States I understand) and all figures are Rear Wheel Horse Power (RWHP). Base run produced 301 RWHP and 282 Tq. As this was lower than expected and the Ford Motorsport 'shorty headers' & exhaust on our cars were suspected as being the most likely shortfall, the exhausts were cut off just in front of the mufflers to reduce backpressure.

2nd run produced 287 RWHP and 300 Tq with airfuel ratio up around 18:1 indicating that we were on the right track and more fuel would bring the Hp & Tq figures up. Jets were changed to 75 primaries and 85 secondaries.

3rd run; 313 RWHP @ 5700 and 301 Tq @ 4750 (with the air fuel ratio still around 14.5 - 15:1 so more power there still if we had rejetted again).

This result confirmed that the exhaust on our cars is a primary restriction for those wanting to get over 300 RWHP out of the current set up.

My intention is to now build a new exhaust header system based on 1 3/4" tuned length primaries, merging into a 4" single system on the right hand side of the car. Cam may also be retimed and we will play with carb spacer and ignition timing. Comp ratio will remain the same as I am leaving heads at present combust chamber cc so that they will produce 10 to 1 comp on a 347 or 358 engine in the future.

I have another 5 liter V8 race engine that has produced 466 RWHP & 360 Tq on this same dyno so I will be disappointed if we do not get to around 340 - 350 RWHP and 320 Tq with the above combination.

A couple of watch outs on this project were the height of the Procomp HEI requiring the use of the 1" carb spacer so that the aircleaner would clear the top of the distributor cap. The other was the need to notch the pistons which was really easy after the purchase of an Isky notching tool. No need to use a machine shop for this job.

Another discovery was that not just the block is weak in these late model 302 engines. The factory 302 crank is of a 'lightweight' design where the centre counter weights are very small. This is compensated for with the 50 oz external balance. Amount of external balance means that the offset weight in the balancer on the snout of the crank produces a bending force at over 6000rpm that can lead to crank failure. I am limiting my engine to 6000rpm as a result.

Hope the above is of use to those of you modifying GTRA engines and interested in others experiences.

[Blue Streak 21]

I've made similar mods to my 302. I went with Canfield alum heads that have 2.02" intake valves. The heads are fully ported. The cam I installed is the Ford Racing B-303. The cam came highly recommended even though the lift is only 0.486". I thought that since I was staying with the stock pistons, I should not go crazy with lift initially. I went to Scorpion full roller rockers with the stock 1.6 to 1 ratio. Stayed with EFI, but increased the intake size by going with a Typhoon manifold which is a copy of the Edlebrock RPM intake. I matched up the intake with a 75 mm throttle body and matching mass air meter. Intake was match ported to the heads and TB.
I checked piston to valve clearance with putty, and found it to be pretty close (less than 0.020" clearance). I ground a greater fillet on the notches for the intake valve, and this gave me the required > 0.080" clearance. I used a pneumatic grinder. This would have been easier if I had used the tool you recommend. Oh well, live and learn the best tools to do a job.
The engine runs very well. The lope of the cam is nice, and it still idles well. I have good power to 6000 RPM. This is much better than the anemic 5400 RPM limit of the stock motor.
I have not dynoed the engine yet, but plan to in the near term. I'm hoping to get 320 + HP at the rear wheels, although I expect that I too will be limited by the restrictive shorty headers, and stock 19 lb injectors. Injectors are a dime a dozen, but long tube headers are a different story. I wonder if there are factory made long tubes that will fit our application? I think the WS cars have long tube headers on the 351 motor.
I have run the car at my home track (Sandia Motor Speedway), and have decreased lap times by about 2 seconds per lap. I'm okay with the improvement, but as expected, I'd like a bit more HP.
I'm already thinking about the next engine mod. What do you think about droppin' in an all aluminum block 350 ci motor. Save 50 more pounds and add a few more Cubies. Might be an GM LS1 motor. Kinda weird, huh? Chevy motor in a Ford.

Jerry

[NZGTRA17]

Jerry, will be really interested to see how your combo goes on the dyno so keep us posted.

Yes I contemplated swapping an LS1 or LS2 Chev into the car but as it is the only Panoz in New Zealand (road or track that I am aware of) I decided to keep it reasonably 'original' for the time being.