New Air Cleaner Housing

[L31MaxExpress]

A little lean and too much timing at WOT, but it pulled smoothly up to speed.

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[Road Trip]

Re: IATs vs cramped engine bays/loss of engine power.

Although we didn't have instrumentation, the loss of power + pinging once the cramped
'75 Monza engine bay got a good heat soaking was not subtle. Of course we
were feeding the Q-jet with a conventional underhood air cleaner.

The solution that we used was to mimic what the Chevy engineers
did for the '68 z-28 Trans-Am racers. (Picking up cool air from the base of the
windshield.) Although no pictures survived of our home-brew setup, it looked a lot like
what we were using as a guide. (See photo of the '68 Camaro engine bay.)

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Solved our problem, much improved after the fact. Semi-unexpected side benefit was
that when we got into the secondaries it was like being in the front row of an internal
combustion concert... :0)

 

[L31MaxExpress]

Re: IATs vs cramped engine bays/loss of engine power.

Although we didn't have instrumentation, the loss of power once the
engine bay got a good heat soaking was not subtle. Of course we
were feeding the Q-jet with underhood air.

The solution that we used was to mimic what the Chevy engineers
did for the '68 z-28 Trans-Am racers. Although no pictures survived
of our home-brew setup, it looks a lot like what we were using as
a guide:

You must be registered for see images attach

Solved our problem, much improved after the fact. Semi-unexpected side benefit was
that when we got into the secondaries it was like being in the front row of an internal
combustion concert... :0)

Hahaha, I thought that was only the old Mercury 2-stroke 1150 tower of power I6 with the induction behind you. Our 115 hp with triple carbs, sounded like you were about to get inhaled into the engine when you rammed open the throttle.

 

[L31MaxExpress]

Put enough miles on it to datalog the PCM and fine tune the MAF table. I also re-visited the VE tables and have them very close as well. Running extremely well now. Rolling along at 70 mph at 17.5:1 AFR. One thing I have always run across on GM and Nissan. You can either have the speedometer in the vehicle correct or the PCM correct, speedo always reads 2 mph faster. I set the tune so that the speedo is correct at 70 mph.

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[L31MaxExpress]

Comes alive so hard I had to feather the pedal for traction.

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[L31MaxExpress]

Looking through some old video clips, I found this old clip. Same exact section of road. The van was ~700 lbs lighter back then, had a 9.5 SF 14-bolt with 3.73 gears and the stock 15" wheels with shorter P275/60R15s all the way around. Had a cammed 5.7L, marine intake, thorley tri-ys. I also ran across an older tune from this time period. At that time frame the tuning guides all suggested Zeroing the torque loss spark advance table. That effectively deleted torque management and shift torque reduction. That alone was really beating on the driveline compared to what I have now for tuning. Just felt the comparison was interesting. It pulls so much more smoothly now and it is not nearly as abusive to the driveline as it was during the WOT upshifts. Definitely a more refined shift than it was. Also despite more weight and an overall taller gear ratio, it definitely moves a bit better now. 383 cubes and aluminum heads for the win. The old Express van was no slouch with the 350 either although to compare it to what the 383 is pulling around now, the van would need a 4.10 gear to compensate for the increased tire diameter and the van would need most of the interior pulled out of it to put it on a ~700 lbs diet.

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