3500 swap questions

[Superdave]

Right sized as in say the 3.4 injectors?

I want to ensure I am not maxing the injectors I put in it out, I want plenty of headroom so that is why I am kind of unsure of the 3.4 injectors seeing since I'm not far behind you in mods, but your injectors are much bigger.

my goal was 300 WHP, that's why i'm running such big injectors.. i swapped out the FPR to the lower PSI one for now.. i'm going a little lean in the top end but i've still got plenty of injector to handle it.

[PCGUY112887]

I hope to be able to hit 250WHP, it's kind of a long shot but I think I will be able to get close after exhaust, custom ram air, and a damn good tune.

I would go with an under drive pulley to try to pick up some extra HP but I still don't like the whole idea of it not being an insulated pulley or whatever people talk about who say it's bad for the engine in the long run (something about it transmitting vibrations to the crank).

[Superdave]

hundreds of people are running the FFP pullies w/o problems. Sure in theroy it's bad.. so is drinking beer

[Guest]

looking into putting one of these in my '88 retta minus the already mentioned issues(crank trigger, fuel rail, fpr,vacuum lines, power sterring pump, tuning) what else might pose a problem? people are saying the mounts definetly, but others are saying no. anyone have any idea about this and a remedy for it?

MNount or mounts, will definatly be an issue.

If you don't mind waiting a bt, I'll be making the 3500 mounts soon, since I am getting a 3500 on Sunday, and will design the mount(s) from there. I am also thinking about making some other parts to make the 3500 swap easier.

[Joseph Upson]

What if anything has anyone done to try and optimize the spark table for this engine?

I discovered sometime ago that you can modify a rich/lean condition by fuel map changes, or by timing changes. Since you're dealing with a slightly different combustion and compression ratio it is obvious that the timing might be off by quite a bit.

You should see the difference in the Main spark table for the turbo 3.1 compared to that for the Fiero. On my install I plan to start by insuring my injectors are scaled relative to the ones the Bin code was programmed for by comparing the specs to the replacements for flow pattern consistency.

For example, the 3.9L uses Multec 1 injectors from what I read so if the 3.1 used Multec 1 injectors the response to the computer should be similar and since they are already sized right for the engine it would be good base start.

I'm going to tackle timing like this; raise the rear wheels off the ground, setup my datalogging equipment, pull up the main spark table in the emulator,
let the car idle at say 800 rpm 30Kpa and increase the advance at that particular rpm and MAP Kpa until I get a knock count and then back timing off 3 degrees from there.

Then I'll increase the whole Kpa column by the new advanced amount for each rpm row, put the car in 6th gear with wheels off the ground, engage the clutch and use the brake and accelerator to hold engine rpm near steady to allow me to reach the upper Kpa points in the column at 850 rpm to check for a knock count at any location to make sure my current increase if any is not causing spark knock anywhere in the column.

Putting the car in high gear at low speed will make it difficult for the engine to over power braking so that I will be able to reach say 100 Kpa at 800 rpm and hold it long enough for a reading.

Usually on the road when you go to wide open throttle from a stop you have already reached several 100 rpm before 100 Kpa is reached for the lower rpm you are trying to get it for.

Then I'll do the same for the 100 Kpa column by each of the tables rpm labels, and make an appropriate scaled increase or decrease to the remaining table values which should outlined by two modified areas in the shape of an "L" , bottom left to right, then up. Over time I could test more of the cells individually for more accuracy. If the timing table is right efficiency and response stands to gain a lot and might get rid of a lot of rpm range troble spots, like idle.

[EspanolaGuitarista]

Could someone...

give me a quick run down for a california car swap?

[Superdave]

give me a quick run down for a california car swap?

Engine swapping is known to cause cancer in California, sorry

[PCGUY112887]

I read the 4.2L Trailblazer injectors will work, and that they are #28 injectors (which also means 28lb/hr?).

I want injectors that are going to be enough for future mods, if stock is #24 seems like #28 would be good? Are they a direct swap onto my 3100 fuel rail?

http://cgi.ebay.com/ebaymotors/NEW-FUEL-INJECTOR-2002-2004-GMC-ENVOY-12569573_W0QQcmdZViewItemQQcategoryZ33554QQihZ006QQitemZ160093369955QQrdZ1QQsspagenameZWD1V

ACDelco # - 12569573

Thanks.

[SappySE107]

As long as you are using your 3400 fuel rail, that is fine. They use the multec 2 connector (00+). You can get the connectors and wire them up to your harness in place of your current connectors.

[Superdave]

those will fit the 3100 rail just fine... they are Multech 2's so you'll have to find a M2 harness at the junk yard to cut the ends off and put on your harness (if you don't allready have a multech 2 harness).

#28's should be more than enough to support 250 WHP.

Moonwell's sitting at 80% with his #22.5's at around 240 WHP.

[PCGUY112887]

Humm I didn't really want to have to rip the wiring apart and buy injectors then buy another fuel rail to rip the connectors off...

Any other suggestions that are multech 1 injectors? I would just get some #24 3.4 DOHC injectors but I am afraid they will end up being too small (planned on using stock fuel pressure).

[Superdave]

Humm I didn't really want to have to rip the wiring apart and buy injectors then buy another fuel rail to rip the connectors off...

Any other suggestions that are multech 1 injectors? I would just get some #24 3.4 DOHC injectors but I am afraid they will end up being too small (planned on using stock fuel pressure).

the #24's should be fine, it's very easy to swap the FPR out for the newer 55 PSI one.

[PCGUY112887]

Superdave I know that you used a 3400 timing cover with the 3400 timing cover gasket on your 3500... would there be any problem using the 3400 timing gasket with a 3100 timing cover, or are they the same?

Any "tricks" to sealing this big ol cover up? One of my main worries about this going in is a leak from a seal like that.

Also, any chance the O2 sensors that are on the 3500 would work with my 96? How "bad" would it be to only monitor 1 bank vs having a bung made in a wye pipe after the manifolds connect? (that is if I use the header style manifolds).

Still waiting on some sort of reply from the guy with the 3400 crossover manis with big ports

[Superdave]

I used the 3500 timing cover with a 3400 gasket. it appears that the pattern never changed. Your 3100 cover should bolt up w/o problems.


I was told the 3500's o2's wouldn't work, i ran one for a while and got some weird values so i switched back to the 3400 one.

i usually run ultra-black or ultra-copper around both sides of that gasket, you also want to bead up some in the front where the cover sits on the lip of the pan. Putting some in the keyway for the crank pully is also recommended.

[PCGUY112887]

So you actually goop it on each side of the gasket when you put it on?

As far as the keyway, is that just the slot that makes the pulley go on a certian way?