[thirdgen455]

I got the IAII block out of the Boss Bird today. So I'm one step closer to my twin turbo Pontiac. First I will be running my 455 HO block with a Luhn YSI setup. I'm probably about a year out on the turbo's. I'm only finishing the heads and wiring the car from the YSI deal.

[er455]

Are you running a turbo 400 trans and have it shifting in auto with 1,000 hp ? At 17# of boost what is your timing set at ? And what is your rpm limit set too?? I have the check valve as well and it doesn't want to shift after 14# of boost going to try to add another check valve soon .i have a 455 with added 4bolt main caps and a 4.250 stroke crank in it , was told to keep it at 5,600 rpms to live ......

[taff2]

I have a full manual TH400 in my race car, but have a couple of customers with Auto TH400's and TH350's behind 650-1000hp blown street engines. Have you put a 0.050" restrictor in the vac line before the tee? Just push a short length of ali bar with a 0.050" hole in it into the tube. 27 degrees of timing , rpm is 7000 on my car.

[er455]

Thanks taff2 I don't have a restrictor in line I will try that though thanks for the tip 👍

[GoatRider]

A few posts back someone mentioned with an LS motor you could use a stock (cheap) computer to control fuel injection. Why can't this computer control a Pontiac? I assume there is some sensor or more than one built into a fitting on the LS that is difficult or impossible to fit on the Pontiac? Cam sesnsors and such??

[er455]

Good question Goatrider I don't think the ls motors have a distributor and they have a crank sensor so not sure if it's possible

[Tom Vaught]

You would have to run separate systems: Magnetic or optical trigger for say a MSD ignition and the cheap LS computer for the fuel control. No spark capability.

Or you could run the cheap LS computer with a common 62-1 crank sensor and a BOP cam sensor (driving the oil pump) and the LS computer would not know the difference if the engine size was close. It would not work well if you put a 5.3L LS calibration computer on a 400 or 455 engine. If a tune up shop had the right software THEN THEY might be able to modify the LS software for the larger engine but it would be a crude calibration as the ignition maps would not match well with the pontiac engine even if you got the fuel close.

Tom V.

[Don Keefe]

I think that a Megasquirt system would be a better alternative, as it can be made to control everything- fuel, timing, boost, water/meth injection. It's very sophisticated and not terribly expensive for what it does.

[BruceWilkie]

Originally Posted by Don Keefe

I think that a Megasquirt system would be a better alternative, as it can be made to control everything- fuel, timing, boost, water/meth injection. It's very sophisticated and not terribly expensive for what it does.

MS3 Pro would be my choice and the software isn't hard to learn(plus self learning feature which can be turned off and you can manually refine if you want).

The LS boys usually ditch the stock ECU at some point. Especially running the big cube aftermarket LS varients.

Holley also offers a similar EFI package(for more $) and they both have a boat load of features. Forum arguments over which is better are like Ford vs Chevy VS Dodge lol Not hard to stir a hornets nest!