jmr302

Does anyone have any flow numbers for the MR or the SR? How about siamesed or large runners?

There's an option for "TPI intake" but I still don't know what "Induction Flow" value to use. I tried 660cfm@1.50inHg, and the hp/torque values are about what I'd expect but just thought I see if anyone had specific info on this.

Thanks!

Cruzin I-5

I was playing with my desktop dyno also and had the same questions.......
Where did you find the stock config file for the stock L98?
what #'s are you using for the heads?

jmr302

I didn't find a stock config file for an L98. Wish I had one. If anyone is willing to share one they've developed it would be appreciated. Since I'm not using an L98 longblock anymore I modelled what I had (see sig).

There is an option for a TPI type intake in there. You still gotta choose an induction flow rate though.

DOCTOR J

In Sept 2000 GMHTP published these flow-bench #'s for an L98 head.
(The table lined up when I typed it in)

Lift - - Intake - - Exhaust

.05 - - 30.18 - - 22.78
.10 - - 58.23 - - 47.33
.15 - - 90.44 - - 70.42
.20 - - 116.6 - - 94.01
.30 - - 158.4 - - 126.0
.40 - - 185.0 - - 145.0
.50 - - 193.1 - - 160.6
.55 - - 193.1 - - 162.2


HTH
DrJ





[Modified by DOCTOR J, 1:33 PM 2/27/2002]

scorp508

I think our MAF only supports 550cfm ungutted, and something like 725 gutted.

dtorc4

Thank you Scorp, I was curious about this too. :cheers:

-=Jeff=-

But keep in mind.. the ECM is still restricted by the MAF.. it only allows the ECM to see a MAX value of 255 GM/s

HighHopes85

Here's some other flow stuff...

http://dtcc.cz28.com/flow/index.htm

-Matt-

Aggravated4life

A book I have quotes "realistic"426 cfm for the 350 TPI motor,assuming 80% VE.
(didnt say if it was for the TPI only but more like the entire motor)
532 cfm is for 100% VE,but isnt looked at for measuring unless forced induction of some kind enters the picture.

Anyone thinks this is pretty accurate?
:)

NoWorries

Hey Bill, that sounds about right, I seem to recall 620 CFM as being posted a long time ago, but I can't site any sources. That may be for a throttle body or something.

All I know is that my poor car is suffocating!

NoWorries

Oh yeah, also, shouldn't we be able to tell where its hurting if somebody had a dyno sheet of a stock motor? A 350 only needs so much air, so you wouldn't notice a deficiency down low in the range, only when you get higher.

The formula for necessary CFM is

Isaac just did a mostly-stock Dyno I believe, we could probably use his.


[Modified by NoWorries, 7:16 PM 2/27/2002]

NoWorries

Ok, he doesn't appear to be on, and so I don't steel April's bandwidth, I uploaded this to my website, but its "NoOrdinary91"'s Dyno:



I looks to start dying at 4000 rpms, so using the formula, assuming perfect combustion(which is unlikely since they're over 4000 ft) we see that:

350x4000
--------------
3456

Its making 405 CFM, which doesn't really sound right to me, but then again, I don't know what I'm talking about. :)

Aggravated4life

Hey NoWorries,
I wouldnt be suprised to see the cfm in the low 400's.Keep in mind the entire system is DRY with no fuel flow, so its not as bad as it sounds.A 600 cfm WET intake engine is probably going to flow similiar to a dry intake engine that flows 400-500 cfm.I may be wrong,but its what I was told.Im always open to corrections anyways.
Its a reason alot of mods dont really work on a stock motor...you throw on the biggest TB and MAF sensor but the stock designed already exceeds VE of the entire engine set up itself.
BUT,changing them allows one to change pressure,faster mass of air build up into the motor and in a sense a little more torque/power.

Going back on topic,I would also like to see specfic flow numbers for the miniram itself and other set ups.Just interesting for me to read more about them.
I also think engine speed/rpm and intake runner length plays an important role in power rather then just looking at flow sizes.
Thats probably why the stock TPI,even though VE wise is fine for feeding a 350 pretty well, is restricted at a certain engine speed over time due to its long runner length.
Man I wish I was a guru at this...lol...sometimes I confuse myself.
:)

NoWorries

Hey Bill,

Thats a good point about dry vs. wet, I didn't think of that.

The guy that put the motor in my friends pick-up truck has a 1982 Camaro with a Supercharged 383, he ran a 12.7 one day at Firebird raceway, then went home dissapointed. He designed a system that encompassed the fuel lines after they entered the engine bay and replenished it with Ice Water after each run. He was able to run a 12.1 the next week. He couldn't account for barometric differences, which I'm sure there were some, but if you think about it, it is a super cheap N*S system, as it is cooling the air, making it dryer and denser, therefore fitting more into the cylinders. Something that I may have to try some-time. :)

NoWorries

Back to the original question, when I did my desktop dyno run, I first determined that I had 210 rwhp and 310 rwtq before doing any mods. As I specified below, I used the value 620 CFM. I'm not sure how much that changed things on the top end, we'd probably see hp top off sooner with a lower value:

dgoodhue

I read that at the "Tuned" frequency of the TPI (~3200 rpm) the VE is 103%. Yes, a slight supercharging effect.

jmr302

Thanks, NoWorries. That's what I wanted to know. This was the last variable to setup for my engine. Since it's never been on a dyno I really had no idea what hp and torque curves this engine would make. The company that made this longblock quoted all that information based on a carb and single plane intake setup. TPI changes everything.

For those of you that haven't used Desktop Dyno, I don't think the program differentiates between fuel&air or air-only flowing intakes so for EFI engines you end up having to use that "induction flow" as a fudge factor to sort of adjust the results. This is fine if you've had your car or engine on a real dyno. Kinda pointless if you haven't. I think if you're running a carb you just put in the carb's cfm size.