Circle Track 3.1L (Modded)

[ForcedFirebird]

4. If you wanna get more wild then you could use a '00+ 3100, swap in a 2.8 MPFI crank, 2.8 RWD pistons (.040" overbore) with 3500 heads/LIM and a large port 3100 UIM, Camaro 3.4 headgaskets, decent reground cam and a set of 3500 exhaust manifolds.

Isn't it going to take more that .040 over to fit the 3500 valves? Ben has some pics of the 3.1 heads gaskets on the 3500 head, and the valves won't clear.

And this is better ?? Come on FF, you going to make me drag every speed secret you know out of you ?!?!

No secret, I need bigger injectors (than stock) to fuel my turbo. Here's some more info...

http://www.rceng.com/technical.htm

You are going to have to tune for the larger injectors, or the car won't even idle.

[Superdave]

ok, so with my limited understanding of circle track racing the basic idea is to have an engine that will be:

A. Lightweight to help with turning
2. Have enough torque/HP to get you up to speed right out of the corners
III. Enjoy high RPM's
D. Look Stock


I can think of a few combinations i'd use, all would be pushrod...

First question, does it have to sound stock? Like if you pull up for Tech and it's idling like a 9 sec dragster would they let it pass? lol


all the Gen3 style engines love the higher RPM's... you can go a bunch of different directions with that.

1. 3500 swap with a blank or large port 3100 Plenum (and maybe a bored TB) With 3500 "header style" manifolds

2. 3400 swap, Camaro 3.4 pistons, 3500 heads/LIM with a large port 3100 plenum, bored TB, 3500 "header style" manifolds

3. Either of the above with a custom ground roller cam. Keep the LSA in the 112-114 range, around .510 lift and 270 advertised duration. Should keep it idling fairly decent.. Also a trick that seems to help is to decrease your spark advance at idle, makes the idle much more "lazy" instead of choppy, might fool a judge...


4. If you wanna get more wild then you could use a '00+ 3100, swap in a 2.8 MPFI crank, 2.8 RWD pistons (.040" overbore) with 3500 heads/LIM and a large port 3100 UIM, Camaro 3.4 headgaskets, decent reground cam and a set of 3500 exhaust manifolds.


For injectors i'd go with #24's atleast.. i'm personally running #32's and they seem to be working very well.

[communityracingchallenge]

Yep, I have 24# blue top Denso from a Ford Mustang.

And this is better ?? Come on FF, you going to make me drag every speed secret you know out of you ?!?!

As a further aside.. we lost the 3.1 motor over the weekend.. got hot and siezed up.

So this "upgrade" thread is now a "rebuild" thread.

[ForcedFirebird]

I was asked today if I was going to change my fuel injectors to the v8 type, since they flow more and fit right in.

Never heard about that before.. is that an option anyone has tried.

Yep, I have 24# blue top Denso from a Ford Mustang.

[communityracingchallenge]

I was asked today if I was going to change my fuel injectors to the v8 type, since they flow more and fit right in.

Never heard about that before.. is that an option anyone has tried.

[sharkey]

in your car somewere there will be a plug like this


all gm's with computers till 94 had that plug. its a standard gm diagnostic plug for gm obd1. if you dont have one in the car (usualy its under the dash on the drivers side) its been removed.

[communityracingchallenge]

I have a 91 grand prix, and its obd1. Its the setup I learned to tune on. I can do anything you want to if if you stay naturally aspirated

You have a gen 2 motor, which will look nothing like a 3400 upper intake. You can do a hybrid swap. You have a flat tappet cam, so comp, crane, crower, lunati, etc make cams for it.

You would need a 3400 block to use the camaro or DOHC pistons. camaro give 10.8:1 and DOHC give you roughly 13:1 with 3400 top end.

Then it must be a 90 Grand Prix, because the connector was a flat 4 pin type prong, not the OBD1 connector.

[ForcedFirebird]

I have a 91 grand prix, and its obd1. Its the setup I learned to tune on. I can do anything you want to if if you stay naturally aspirated

You have a gen 2 motor, which will look nothing like a 3400 upper intake. You can do a hybrid swap. You have a flat tappet cam, so comp, crane, crower, lunati, etc make cams for it.

You would need a 3400 block to use the camaro or DOHC pistons. camaro give 10.8:1 and DOHC give you roughly 13:1 with 3400 top end.

The 3.1 Camaro with 3400 heads give 12.xx:1 and the 3.4 pistons with 3400 heads give 14.xx:1 according to the CRcalculator IIRC.

Tuning equipment can be had cheap from Moates for your car.

[SappySE107]

I have a 91 grand prix, and its obd1. Its the setup I learned to tune on. I can do anything you want to if if you stay naturally aspirated

You have a gen 2 motor, which will look nothing like a 3400 upper intake. You can do a hybrid swap. You have a flat tappet cam, so comp, crane, crower, lunati, etc make cams for it.

You would need a 3400 block to use the camaro or DOHC pistons. camaro give 10.8:1 and DOHC give you roughly 13:1 with 3400 top end.

[communityracingchallenge]

Okay.. I found a minor error, getting ready to start the job, discovered that this car is a 91 Grand Prix. Not a 94. Working with Race Cars which don't have dashes in them or door stamps, sometimes this information gets lost. So I have an ECM, its not OBD1 much less OBD2.

So this is going to be the process..

Step 1) Pull motor out of car.
Step 2) Disassemble top half and bottom half.
Step 3) Pull Oil Pan, Remove Crank, Drop Pistons.
Step 4) Replace Stock Pistons with 3400 Pistons (DOHC or Camaro ?)
Step 5) Fresh Rings and Oil Pump.
Step 6) Reassemble bottom half.
Step 7) Remove intake manifold, exhaust manifold, heads and plennum.
Step Replace everything with 3400 parts - except
Step 9) Use custom ground high performance cam
Step 10) Use 3500 plennum
Step 11) Reassemble top end
Step 12) Put back in Car
Step 13) Go FASTER !

Questions:
1.) Are we sure that all the parts above are plug and play ?
2.) Is the electrical going to work, or are new sensors/modules needed ?
3.) Is the computer adequate or is all work going to be lost with old computer ?
4.) Can a chip or "hotter" ECM be purchased ?

Are there tranny mods which would be benefitial ?

Any other go fast ideas ?

Thanks,

Patrick

[ForcedFirebird]

what is IIRC ?

If I Remember Correctly

[communityracingchallenge]

what is IIRC ?

[ForcedFirebird]

You can leave the engine in the car, if you can pull the pan to unbolt the rod caps to change the pistons. In my car it's possible, but don't know about your FWD. You can't covert your 3100 into a 3400 because the bore would make your walls too thin.

If you use stock sized pistons (3.1 Camaro/Firebird), you won't need to bore, just a hone will be fine (depending on condition of the cyl walls), but the bore would give you a few extra cubes.

Since you have aluminum heads already, your brackets etc should work fine with 3400 heads, same gaskets as if you did a rebuild.

First decide on where you want to go with this. Are you going to keep your block and do a top end swap, or are you going for a different motor?

For a top end swap, start by finding heads with the casting numbers given to you. If it's out of a JY, them get the manifolds etc as well.

Don't know what kind of budget you are working with, but Ben sells all the top end stuff new here on the site (and he can re-grind a cam for you IIRC)

[communityracingchallenge]

Something else the car really needs.. it turns like a tank.

I need a way to get 8 to 10 degrees camber into the right front.. any thoughts ?

[communityracingchallenge]

okay then.. lets break it down.

Do I need to pull motor out of car or can conversion be done in car ?

Are there are parts like gaskets, seals, brackets, mounts, so forth which are needed ?

How about computer stuff, sensors, wiring harness, mods, over drills, re-drills ?

Can we maybe put together a Step 1 do this, Step 2 do that type of list ?

Seems to me some stuff is simple and just swapping parts.. otherstuff like over boring the block and/or shaving the heads are more expensive.

What about a valve job, what about porting..

And is this engine I want maybe for sale already on someone's bench ?

OR maybe some Mid-Western (Michigan) 60* V-6 Engine Builder would like to join my racing effort and get some hands on grease going..