Ed Maher

Effective immediately, this will be the redundent question thread. If you know a question that is constantly asked, yet has a really simple answer, put it in here. From then on, anytime someone asks that question I will lock it and remind them to read the stickies.

Also, I reserve the right to edit this thread in the event that I don't think that something should be here. Also, the same general rules as the index/FAQ thread, please don't waste space with sigs or the like. Just a Q and A please.

Note, this isn't meant to replace the FAQ/Index sticky. I still want to see people add useful info to that as well. This is just a thread to serve as a help for those that need answers to easy frequently asked TPI questions.

Ed Maher

Q1: What shoulld i set my AFPR to for maximum performance.

A1: There is no specific setting. An AFPR is a tuning tool. Go to the track, get a G-tech, borrow a sundial, but find some way to measure your cars performance. Then see how it changes when you adjust the AFPR. Usually helps if you ensure as much consistency as possible, i.e. same road/track, same conditions, wheelspin under control, etc.


Q2: Where should i set my timing?

A2. Read A1 and pretend timing is setting the AFPR

rezinn

Q : What is a stealth ram/ miniram/ superram? Are they smog legal? What are the advantages, etc?

A : http://www.thirdgen.org/techbb2/search.php?s=

Q : Should I put a 58mm throttle body on my stock engine?

A : http://www.thirdgen.org/techbb2/search.php?s=

(feel free to edit this if you want to actually insert real answers)

CHRISMAN2000

Q: Which intake is the best Mini ram, Accel intake, or super ram.
A: Buy them all then do your own testing. Then let us know.


edit: Also, do some searching. Over the years a few members HAVE posted comparisons between the intakes. 2 names that come to mind are Mike Davis and grumpyvette (probably mispelled) But noone is just going to repost their findings cuz some newbie is asking, just search it out and you'll learn more.

Steve89GTA

Q: Why do my rear GTA rims look smaller than my fronts?

A: GM designed the rims this way on purpose. The front rims appear to have a deeper 'dish' and it is perfectly normal.

madmax

Q: What 58mm throttle body should I buy?

A: None.
If you had to ask, you dont need it. Do the exhaust, intake base, cam, and heads, in that order (many do heads and cam at the same time... makes sense). Sometime after you start running 12's, you can think about a different TB, otherwise you are just wasting your money.

formul8!!

Q: What intake should I put on my TPI engine?


A: Depends what you want to do with the car.

1) Street or autocross- Stick with the Long Tube runner for low end torque. Maybe a Super ram also.

2) Drag Racing or road course- Try a Super Ram, miniram or Holley Stealth Ram- to move the power band higher and be able to move more air at high RPMs.

John Millican

Ed, timing is set in the ECU on a TPI car. It is only adjustable by reprogramming the prom.
Changing the base timing at the distributor is only lieing to the ECU and could hurt perfromance.

__________________

• 2004 Pontiac GTO A4 Black/Black
• Moderator at SouthEast ThirdGen

92 zzz28

When Ed put pretend timing is setting the AFPR from the A1, he meant that to mean that timing will be different for everyone. Just go out and test, make changes according to what YOU find out. No one here can tell anyone where to set their timing, even the base timing is different for lots of posts I have read in the searches.

Macgyver

Hey Ed, a long time ago, Dirk had a "common question" HTML page. I don'tr have it on my hd, but Dirk might, it was in the old http://www.thirdgen.org/techboard3/ directory, titled "common.html"

tpi_roc

Q: Will LS1 heads work with my LB9/L98, SBC1 engine?

A: forget about it.



Q: Will LT1 heads work with my LB9/L98, SBC1 engine?

A: With machine work to the water jackets and coolant outlet yes.



Q: LT1/LT4 Intake shniz?

A: LT1 intake has similar port locations to Gen1 heads/intakes, LT4 to vortec and fastburn. Vortec, Fastburn, And LT4 are "Exceptions" to the standard Gen1 heads with different intake runner locations. LT4's would require machining to work.

Roostmeyer

Q:What about Holley Stealth Ram (HSR) Hood Clearance?

A:It will fit under Camaro hoods w/o any probloms and for a firebird hood you must cut away the bracing above the throttle body such as shown in this thread
http://www.thirdgen.org/techbb2/show...hood+clearance (Stealth Ram install)
This thread also has information on the fuel lines needed.

The HSR will not fit corvette hoods--check out grumpyvette's latest posts as he is working to get a custom plenum made to fit corvettes and firebirds without the clearance work.

Jza

Q: MAF vs. MAP [SD]

A: All flavors considered, MAF is typically better, however, within the scope of thirdgen F-bodies' available factory technology, MAP is the more advanced system and will *support* more power than a 3rdgen MAF based system.

Only planning on doing basic mods (eg. exhaust, airfoil, filter)? MAF is fine. Going to a large(r) displacement motor with A/M heads, cam, etc.? MAP may be the way to go depending on just how wild things get.

Both systems benefit greatly from tuning, and the MAF system's adaptiveness is no substitute for said tuning.

anesthes

To answer the question about timing:

The best route is to set your base timing as _LOW AS POSSIBLE_. This ensures easy starts, especially when hot. 0-6 degrees is a recommended base timing.

Your overall timing (rpm vs load) needs to be done in the prom.

Timing should be (not in all cases!) within 1-2 degrees of knock at every rpm/load point.

To answer the question about fuel pressure:

Your fuel pressure should be set so that at the lowest RPM the
smallest injector pulse can be achieved, and at highest RPM
the LONGEST pulse could be achieved both supplying the correct a/f ratio for your application. There is no 'set' number for any given engine.

The idea here is that, The injectors have a range that they can pulse at. You want your fuel pressure set so you get the correct
lbs/hr at any given RPM range without maxing out the duty of the injector at the high rpm (not enough pressure, injector open too long) or at low rpm, the shortest pulse needs to supply enough / not too much fuel.

Injector pulse width + fuel pressure have NO direct relation to performance, they are simply to make sure your operation range and powerband match.

-- Joe

anesthes

I figured that out once. At sea level it was 540cfm. I think even 420HP is being generous. But also keep in mind, you can staticly
control fuel based on RPM after that (in the prom). I'm not saying
this is wonderful!

I absolutely agree with you with porting. I thought TPI was nice before the blower. Now that I'm blown, I almost wish I went LT1
or TBI even.



-- Joe

Iroc n roll

Just a minor correction here, the MAF can "read" higher than 255 gps but its in the 8-bit ECM where the 255 limit is reached due to the fact that 255 is the highest number possible in binary code for an 8-bit. So before people start asking "will an LT1 maf solve the problem?" they should know their ECM is the culprit

__________________
-1985 IROC-Z w/T-tops - The LT1/L98 *sold*

www.GKEonline.com

anesthes

Very good point.

8 bits (11111111) = 255

The reason GM didn't assign an additional byte was simply because the code would have to check if the first byte was on before referencing the second byte. That would be. Messy..
If your a coder you'll understand this.

A 10 or 16bit ECM would be the solution for this issue with MAF.

-- Joe

Iroc n roll

Yes, hence the reason why LT1 owners never complain of MAF troubles....they have 16 bit computers (IIRC)

anesthes

I'm sure there is a better thread for this, and if a moderator chooses to delete/move it to its own post it thats fine...



I thought about this yesterday. My 68HC11 assembler book talks about a instruction, I think itd ADDB what it does is combine two 8 bit registers into a fake 16 bit register.

I think the problem is actually in the driver for the MAF, I think the driver is designed to utilize only an 8 bit signed register (-127 to
+127) which is hardware, I think.

Otherwise, I don't see why someone wouldn't have just hacked the code a looong time ago.

-- Joe

Iroc n roll

Interesting, I remember that Vader (i think) was doing alot of research into this topic with the goal of beating the 255 limit. I wonder if his findings concur with yours. I think you're on to somthing though. I also think most of this should be moved to form its own topic, with the exception of the post saying that the problem is not in the MAF sensor but in the computer.

Vader

Yes. No. Yes. Yes.

This should really be it's own topic.

__________________
Later,
Vader
- - - - - - - - - - - - - - - - - -
"Everything should be made as simple as possible, and not one step simpler."

Daimler/Chrysler - Inventor and sole patent holder of the internal combustion transmission.

ICON Motorsports

RBMZ28

In reply to the 255 limit of the maf.....there is plenty of info on the diy chip burning section of this site.Generally speaking you would have to have a relatively stout motor (mid 12's is my guess) to exceed this limit.The problem is the ecu won't read beyond this not that the maf is the issue.But thru prom burning (changing the a/f ratio for p.e./wot.easily solves this issue.

__________________
87 IROC WITH 409(.040 OVER400) MINIRAM,NOS(125HP)TRICK FLOW PORTED HEADS,Comp Cam,1/3/4 headers,DIY PROM,MODIFIED
700R TRANS,3200MW convertor,58
mm bbk t.b. 3.73POSI REAREND.
LOOKING FOR THE 11 SEC. ZONE. With new combo current ets.12.13@116.46 mph

86BirdSE

My car runs like crap even though I dropped $3000 in go-fast shiny parts on it... help me! Try tuning it up first.

jrg77

Is the difference between MAF and speed density blatantly obvious when looking? Are there any TPI units to stay away from or are harder to work with? What has to be changed to make a 5.0L TPI work with a 5.7L TPI (I recognize that both will physically fit either displacement engine).

Iroc n roll

This doesn't belong here. Make it its own topic.

Russ-So Cal

Iroc n roll suggested this question doesn't belong here. Actually I think part of it does. He asks three distinct questions. The second and third might rate separate threads, but I think the first one belongs here.

Q. Is the difference between Maf and speed density blatantly obvious?

A. Yes Maf has a maf sensor in the intake hose between the air cleaner and the throttle body. The speed density system has a hose running between the air cleaner & throttle body with no components between.

Asad

What is the stock motor's limit in power and torque?

Iroc n roll

That's a rough question (and a bit vague) and probably doesn't belong here. If you want the stock hp numbers you can look up the hp rating of whatever motor you want. If you want to know the hp limit of any motor you just have to look at its displacement. All power comes from however many joules of energy is released in the whatever amount of gas is combusted, minus however much energy is lost to heat (which is basically most of it). Go here and plug in some numbers:

http://www.GKEonline.com/automotive/hpcalc.html

That should give you some quick and dirty theoretical calculations for a motors hp "limit". If you want more info you'll probably have to post somewhere else..... I'm pretty sure this isn't a banne d topic.....unless all you want is stock numbers....then it is by all means.

__________________
-1985 IROC-Z w/T-tops - The LT1/L98 *sold*

www.GKEonline.com

Iroc n roll

I know it's been almost a year but I might as well take another swing at this one. TPI units from 5.0 and 5.7 motors are identical with the exception that one uses 19# injectors and the other 22# injectors. Other than that the only difference lies in the SBC generation change in 87 when they changed the bolt angle. So 85-86 are the same and 87-92 are the same.

__________________
-1985 IROC-Z w/T-tops - The LT1/L98 *sold*

www.GKEonline.com