Patrick G

iTrader: (14)

Point is, the single plane intake is apparently not the choking point for this application...not with the carb on top. If the GMPP flows well enough to get a 454 into the 9s, it should be OK for a 400+ motor.

Bottom line, most intake elbows and 90mm TBs choke flow when compared to a proper 4 barrell throttle body place on top like the intake engineers intended.

Patrick G

iTrader: (14)

MAF tune, laugh tune. Real men run speed density!!

s346k

iTrader: (4)

i believe the issue is before the intake itself, like the elbow, etc. putting an elbow like that on a single plane basically defeats the purpose of using a single plane.

RoDan

that could be, the long length messes with the flow characteristics. What about the new edelbrock elbows? they look shorter...

Richard@WCCH

iTrader: (3)

If you could run this with a carb you'd see some impressive power. Tests I have seen with LS7 engines running the GMPP single plane with EFI cost over 30hp over a carb setup. This was comparing a 4bbl ttb directly to an 850 carb.
Just for kicks try putting on a borrowed carb and regulating the fuel pressure and run it again on the dyno. You'll be shocked with the results. Warts and all............

Good luck,

Richard

MFIC

Ill trade you my L76 intake LOL.

edcmat-l1

iTrader: (10)

BLASPHEMY!!!!!!
PS they run pretty good too if ya knows how to werks on em....

Howie Felterbush

iTrader: (1)

I agree...A lot of the restriction is the tight radius on the elbow.

Howie Felterbush

iTrader: (1)

Carbs will always make more power than fuel injection. Fuel mixture is where its at. Emissions suck though.

1cdub

iTrader: (5)

The intake is not your problem at all...my intake is completely untouched. It will flow more than enough for a 408....I'm spinning this 454 to 6800. Just trying to help get the facts out.

WizeAss

iTrader: (5)

well.... if someone has a 4 barrel Accufab TB, I will consider trading my Elbow/90mm TB setup for it. If it does better.

Howie Felterbush

iTrader: (1)

pwebb's motor has the same elbow and TB..... although they aren't untouched. the elbow has been epoxied to kill the dead spots in it and increase airflow with less turbulence.

Patrick, im sure you know already but they finally got ahold of the rocker arm guy. You are back in business!!!!!!

Im thinking with the rockers in check you are going to see 760ish with some full pulls possibly even more.

Mike, your combo is soo mismatched it doesnt matter what you do at this time. No one can fix it without spending a good chucnk of chance. perhaps you have the weakest l92 topend setup...Maybe its a record for ya.

hymey

Hmmm, carbies make more power than injection? The motor only sees a certain amount of flow and air speed. Plus fuel mixture. I am guessing the 4barrel TB you tested was 1000cfm. Obviously this motor responded better with and 850cfm carb. If the TB flowed the same as the carb and afrs were the same there shouldnt be any difference. Only being the EFI setup would be more suitable for street use.

I would like to see how it would respond to a Harrop Engineering 8 TB flat slide setup

WizeAss

iTrader: (5)

well, considering I can get the intake ported, and the elbow can be looked at, I dont think I am done yet. The car did make "decent" power. Just not 480rwhp. My heads are fine, and I have a good cam. This new cam did much better and actually didnt fall off until 7000 when he let out. The other 244/248 died at 6200. This one also had much more lowend tq. Rick at Synergy did a good job. He cant fix the 91kpa issue, which can be attributed to the maf/intake/elbow combo.

ONEBADWS6

iTrader: (22)

The motor pic posted is mine. I just switched from an elbo 90mm TB and really didn't pick up much if anything. I did get alot of hp under the curve but I also ported my Vic Jr. which was flowing 290cfm with the heads attached before. But my elbo is noting like the designs you guys run as I can care less about my cowl. Mine was just a 4in 90* pipe with flanges on it.

ringram

Considering a lot of competition engines run with restrictor plates etc Id suggest there are other ways to get air in there other than going big.
How about port efficiency and velocity, cam design etc?
You might have to optimise what you have by changing parts to match instead of using semi mismatched stuff.
Or just force some air in there

Howie Felterbush

iTrader: (1)

Unfortunately its true. The way the fuel droplets atomize with the airstream on a carb vs injection, its generally ~100 crank hp difference. Seen it verified on an engine dyno A/F being the same.

Howie Felterbush

iTrader: (1)

And there you go listening to all the wrong people again. whats new.

Pwebbz28

iTrader: (31)

I agree with PatrickG. Maf tunes are for stock cars. There is NO need for a closed loop tune when you KNOW what you are doing/looking/listening for. Judson @ SAM said himself "Its very hard to beat a two carb setup on a tunnel ram." To me speed density tunes and carbs are one in the same. I REALLY want to try my hand at tuning but my time is EXTREMELY limited.

We had quite a few problems with reversion using a carb on this intake with these heads BTW. Had to use 3 inches of spacer to get it to idle.

hymey

The way droplets atomise?Fuel should spray into the chambers. The combustion chamber sees a perfect amount of atomized fuel per cylinder with efi multipoint. You will get varying afrs with a carb on single plain manifold. It would be more than fuel droplets atomising, more so with air speed,

They used to fit carbs to V8 supercars in Australia when on a budget with single plain manifolds. They lost hp and torque and greater average hp over a 8TB harrop manifold flat side efi. And I dont see motoGP bikes make 240rwhp from 800cc with holleys strapped to them.The aussie V8 supercars make 700hp from 5 L with injection. History shows you are one of few to get such results

In your case a 100hp loss shows something poorly miss matched. That manifold and Big *** 1000cfm+ TB was to big, either that or someone cant tune SD with such a massive camshaft. History shows efi wins the majority hands down.

In Wizes case. A stock 6L will get 99kPa. How you only get 91kpa gets me stuffed. Thats like a blocked vaccum cleaner! A typical efi manifold likes a single TB but single planes work better with a carb or 4B throttle body. That elbow will restrict flow as that manifold isnt designed to work with it. Unless FI is brought into equation.

So there is no doubt a carb will make more over the current setup. How come you dont ditch the elbow and MAF and tune SD, will see results then, only other option is to fit a weiand warrior.

cheers