Will the Edelbrock MPFI system (replacement for small block chevy 87-92) work with the LO3? I know the computer has to be changed but how do you do this? Will it be legal? Will it make approximately as much power as an equivalent TPI system? Any help would be appreciated thanks, Tony

 

I've been working on it over at:
https://www.thirdgen.org/messgboard/...ML/000429.html

Kelly 'GhoSSt' Rosato

 

the edelbrock setup is a short runner system, it would make the same power as a tbi on that manifold

 

Huh? Its a single plane medium runner design. Why would it make the same power as a stock TBI system?

KR


[This message has been edited by GhoSSt (edited December 23, 2000).]

 

he didn't say it would make the same power as stock he said that TBI on the edelbrock manifold would make the same power as the edelbrock with MPI.

------------------
-Tas
'89 Formula WS-6
[soon to be Performace Red =) ]

305, TBI, auto, 14x3 chrome flat based open element with K&N, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

Super GRK_Taz World
EFI & Intake Options
AOL IM: superGRtaz
ICQ 82881207

 

Doesn't make any sense to me. The Edelbrock TBI manifold is a dual plane intake and still saddled with the inherent fuel problems of TBI. The MPFI is single plane, has none of the fuel issues and a much improves runner layout.

My logic points to MPFI being more powerful than TBI, TBI with a Edelbrock intake or even a stock TPI system.

Kelly Rosato

 

picture what he ment: take your new shiny intake, put a TBI on top injectors and all. hes saying that if you run that intake with 8 pico injector OR 2 tbi injectors that you will get the same power.

i.e. single plane TBI or single plane MPI is the same sh!te.

[This message has been edited by Tas (edited December 23, 2000).]

 

It is not a legal system because Edelbrock won't certify it for any thing but trucks.
And it really isn't worth the effort. A magazine article on it showed a whopping 20HP gain (big deal).

 

Tas said it


your current TBI, on your edelbrock MULTIPORT manifold

vs that manifold with multiport


Id like to see where that 20 horsepower advantage goes that edelbrock claims over tbi (yeah thats fair, run a single plane vs an oem dual plane)
It would vanish

 

I don't agree to a point. The volumetric efficiency of a given TB is less efficient when you're flowing both fuel AND air. The fuel is going to displace a given amount of fuel limiting the theoretical maximum amount of horsepower that the injection system can make. By moving the injectors to the runners, the TB is freed to move air only. Not to mention that MPFI doesn't suffer from fuel puddling and suspension issues. TBI has a lot of potential, but it can only go so far.

Kelly 'GhoSSt' Rosato

[This message has been edited by GhoSSt (edited December 24, 2000).]

 

In a flow limited application that would be true, however, 670 cfm of fluid (air and fuel) is more than adequate to support a 350 CI engine

for example, a 350 at 100% volumetric efficiency at 6000 rpm (read: an engine neither you nor I own) will only use 608 CFM of fluid (air and fuel) using the common formula ( CFM= displacement*.000579*RPM/2)

consider that at most fuel is taking up around 1/12th of the fluid that enters through said throttle body (probably closer to 13) and you only gain around 55 cfm of just air, that your 100% VE at 6000 rpm engine cannot use since its allready full of 608 CF of fuel and air, youd need an additional 4 CF of gas on top of the 55 CF you gained to make it burn decently anyhow so now you have the equivalent of a 729 cfm throttle body that flows air and fuel if you are using the 670 to just flow air


I dont even wanna know what you plan on spinning that 350 to if you need all of that


[This message has been edited by Pablo (edited December 24, 2000).]

 

and about the problems with fuel drop out etc, carbs have had those problems since their invention, and they suffer from them even worse than TBI... yet everyone talks up carburetors as the ultimate to support big HP

 

If that were true, why do top fuel dragsters use fuel injection? Mechanical, but FI nontheless. I've never championed carbs.

Kelly 'GhoSSt' Rosato

 

Uh, maybe I shouldnt butt in here but... regarding the volume of gas that a motor is flowing at 6000 rpm. This seems easy enough to figure out because we have an Idea of how much fuel the the motor is consuming in pounds per hour... and we know how much volume a given mass of fuel takes up.

So for the sake simplicity... lets say we have a big HP motor (400 ish) with a pair of 90# injectors at 100% duty cycle. Thats Pounds per hour... so 180 pounds of fuel per hour at max flow... thats 3 pounds per minute. A gallon of gas weighs about 6 pounds so thats .5 gallons per minute... My book says "to convert gallons to cubic feet multiply by .1336806" so that makes our fuel flow about .07 cubic feet per minute.

So unless I'm doing something wrong, a 670 cfm TBI unit is flowing 669.93 CFM air and .07 cfm fuel on a fuel hungry street motor.
I think its fairly safe to say that fuel is not taking up any ammount of the TBI's airflow capability that is worth considering.

 

hmm I know my math is probably off , but consider that 180lbs of fuel may not need all 670 cfm to make a 'correct' fuel mixuture of around 12.5:1 and that infact may be lean (i think it probably is) 180lbs of fuel is probably not enough to make a 12.5:1 mixture out of 670cf

I know my math isnt exactly right, in any case, the air displaced by fuel isnt a whole lot

and Kelly, topfuel dragsters run injection because of the sheer volume of fuel those monsters are ingesting, not to mention, they are supercharged with around 40 lbs of boost

if you want a more accurate comparison to your car i think a pro stock motor would be it, they are N/A and run two carburetors and do so very freakin well such that FI cannot top their setups, it only allows them to use a shorter intake manifold (this from www.theoldone.com ) and as far as i know, there arent injectors out there that can atomize as well as a carburetor when the airflow through it has been optimized as it is in a pro stocker

 

Oooo, this is getting good. Weve got some edukated peples heer. Anyway, I think people are getting very particular about things that they need not be when speaking of a 305's or even 350's that are used mainly for daily driving. Even if you are building a race car, your main power increases are not in your air fuel delivery. Only small perfomance gains can be seen from different ones, all when tuned correctly will yeild close to similar results. If you are an engineer you might start thinking of efficiency. Im certain that they do at GM. However, whether you are flowing both fuel and air, or just air thru a "said" tbi the gains in air, by not also having fuel flow thru those bores are small enough to ignore(or be made up for with a slight head porting or something).

Put the physics books down people. Until your are playing with 700hp motors, you really need not be worried about volumtric efficiency of a tbi vs. a mpfi vs carb....

metaphor. a 400lb football player can loose up to 20lbs of water weight in a game. Now a 180lb guy might loose 5lbs.

A 540cu highly modified engine might gain a nice amount of power by increasing the efficiency of the air fuel delivery system. A slightly modified 305 or 350, relatively, isnt going to gain much at all.

put the ti-92s away too.


------------------
IM: snflupigus | ICQ: 96787192

Snflupigus.com

Open Element Tech Article

ENGINE SPECS:
Stock Rating: 170bhp & 255ft-lbs
305 TBI,Open Element,K&N 14x3,Hypertech Stage I,454 GM TBI
Now Rating: A Little More

STEREO SPECS:
JVC Kalmeleon kdlx3,Infinity Kappa 2way 6x9's,PPI 4x6 Coaxials,PPI PC2400 AMP @ 2ohm
DEI Studio 12" 4ohm DVC,Custom Box:Exactly 1 Cubic Foot

 

just a side note, i read a while back, that top fuel dragsters, breath thru enough air in one pass, to fill the good year blimp.

 

hehe snuff

thats cool! hadnt heard that one

thats a hell of alot of air they are taking in!

as long as its not some idiot inhaling it lol jk

 

btw there more to how much fuel displaces relative to air than just this simple math theres the density of the two, fuel vs air and all sorts of dynamics involved imagine how much air flow is disrupted by just the turbulence in the air stream due to the fuel flying in it etc and the energy required for the air to push the spray cone inward.. etc its pretty crazy the math involved

 

its pretty worthless, the math involved. Granted, fuel is matter, and it does take up space, but thats what atomization is, the air and fuel mix, and now you have thick humid (to use the word) combustable air. whether the air is displaced when first entering the motor or when it is in the manifold, it will displace, and you will always have a volume of space filled by fuel that takes aways space that could be air. So why not mix and atomize the fuel as far away from the cylinders as possible? Injecting o2 and gas fumes would be ideal no?

My arguement is that all the math in the world applied to a fuel / air deliver system on an engine isnt going to yeild very much improvement in hp relativly to other applications that you could apply your extensive thoughts to.

another side note: Ive been reading, and the new technology most are looking next to is direct injection into the cylinder.

------------------
IM: snflupigus | ICQ: 96787192

Snflupigus.com

Open Element Tech Article

ENGINE SPECS:
Stock Rating: 170bhp & 255ft-lbs
305 TBI,Open Element,K&N 14x3,Hypertech Stage I,454 GM TBI
Now Rating: A Little More

STEREO SPECS:
JVC Kalmeleon kdlx3,Infinity Kappa 2way 6x9's,PPI 4x6 Coaxials,PPI PC2400 AMP @ 2ohm
DEI Studio 12" 4ohm DVC,Custom Box:Exactly 1 Cubic Foot

 

Wow...

 

Yeah, the current problem is that no one has an injector (other than diesel) that can survive the combustion chamber.

Kelly 'GhoSSt' Rosato

 

Glad I read this, calculators and Physics notwithstanding cause I guess it all means my TBI is good enough to get me 300plus HP if I couple it with the right motor set up.
My wife happend to look over my shoulder at this thread (she probably thought I was checkin out the porno) and now she really thinks I'm sick cause I find this stuff interesting........bob

 

RSilver, I've got more than 240hp now with a MELLOW (peanut?) 194/214, .395"/.442" Edelbrock 3702 camshaft and custom PROM tuning with some outside dyno/burning/tuning help on 350cid w/9:1. Soon, trying for 300 hp with the genereic (SIS-type) 204/214 cam. If that's not enough cam, gonna try 214/224 cam... I will share dyno results/PROM info with all, if you are interested. I am VERY confident I can get 300hp with the 204/214 cam, though... Noone seems interested in my PROM for that cam, for some reason. I offered to post the BIN but got no inquiries.

GHO, how's it coming? I'd like to "see" the Edelbrock Spark table in the PROM they give you. Just to compare it to the table I am using now, anyways. Don't need the whole BIN for proprietary reasons but cut/paste (??) of Spark table would be a peach. I'll share my spark table with you, if you'd like...

I am waiting to see how your setup runs because I will probably use the Weiand MPFI single-plane (tall!) manifold/rails/reg with an un-injector-podded Holley/Rochester 670cfm TBI as air control, like your Edelbrock setup. It's kliling me to see how yours runs.

 

Well, install is scheduled for Saurday. I'll take pictures and post them and let everyone know my take on it afterwards. Stay tuned.

Kelly 'GhoSSt' Rosato

 

rssilver, you are sick because you find this stuff interesting. But its a good sick, better than lookin at **** sick right? well...

Anyway, ya, ive been reading some stuff in some magazines that come to the shop. Motor weekly or somethin, anyway, even cooler news. saab is working on a variable compression engine. the cylinder is on an axis and adjusts itself. heres a pic/article


------------------
IM: snflupigus | ICQ: 96787192

Snflupigus.com

Open Element Tech Article

ENGINE SPECS:
Stock Rating: 170bhp & 255ft-lbs
305 TBI,Open Element,K&N 14x3,Hypertech Stage I,454 GM TBI
Now Rating: A Little More

STEREO SPECS:
JVC Kalmeleon kdlx3,Infinity Kappa 2way 6x9's,PPI 4x6 Coaxials,PPI PC2400 AMP @ 2ohm
DEI Studio 12" 4ohm DVC,Custom Box:Exactly 1 Cubic Foot

 

Hey Snuf, which shop do you work in? I used to work at Stan Olsen Pontiac, Saab, Subaro MANY MANY years ago. Anywhere near there?

Kelly Rosato

 

You worked at stan olsen in omaha???

Its my parents place. Crarens Auto Air Plus. on 50th and L. We used to do everything including specialize in AC, aftermarket accessories, alarms remote starts, video systems, etc.. We sell a lot. we are a dei dealer, codealarm, computstar and other alrarms. PPI jvc, pioneer, dei, lanzar, and panisonic for stereo stuff. Also distributor for audiovox. We did tint for a while. I worked there over the summer as assistant manager, and sometimes on saturdays now. occasionally i stop by and raid the magazine rack.
anyway. we are somewhat dealerbased, jims dodge and a lot of others. We were doin all of lexus of omahas video systems but i think our salesman snagged em when he quit and went to work for somebody else.

 

Yup, after I got out of the Army in 1987. I think I have a unpaid ticket from the Naz.. err Omaha Police to this day. TOO funny.

Damn. I'll have to make it a point to stop in one day. I know exactly where that is. I bet its changed a lot, but hey, once you're on Dodge, you can find anything.

Kelly 'GhoSSt' Rosato

 

We've got a guy there who has been there for 30 years, ironically, his job before that, was at the dealership we just bought.

Stop on in.

 

Fast, Which 350 do you have that you are getting 240 hp? what heads does it have?
Depending what I end up with, I may take you up on your offer to post chip info.....bob

 

1994 ZZ3 4-bolt main 350cid block, with “the works”
ZZ3 steel crank, balanced and polished
300hp 350cid iron heads, modded to flow 240/195 at .5” lift (waste of money, buy Vortec heads)
Sealed Power flat tops, moly rings, about 9:1 CR
Lunati/Holley H-beam connecting rods
ARP’s in entire engine
Rotating assembly balanced (a MUST for high rpm!)
Clevite bearings, Melling 55 (standard) oil pump
HD oil pump shaft w/steel collar (not plastic)
Edelbrock Performer Intake manifold, no EGR used
Edelbrock 3702 L05 305cid emissions cam (194/214, .396”/.442”)
Edelbrock Performer RPM valve springs
1992 stainless OEM Corvette shorty headers
True 2.5” dual, w/x-over and 3-chamber Flowmasters
Cloyes DR timing chain
FelPro gaskets all around
2400 stall converter w/TH700R4, B&M TransPak
custom Dana 60 rr axle w/4.11’s + minispool
custom rear ladder bars and custom HD frt/rr sway bars
Front axle shackle reversal system
Spring over OR under axle capability (for off-road races)
RS9000 5-way adjustable shocks
custom leaf spring front/rear (National Spring)
31x12.50x15” BFG All Terrain tires on Ultra 10” alum wheels
(Mickey T’s on 12” rims to race fools)
1991 1-11/16” TBI system off ASDU bcc pickup or van
Extra gasket for injector spacer (lots-o-grinding!)
Custom external (bypass) vacuum-referenced FP regulator
Holley TBI to spreadbore adapter
Custom PROM
16 PSI on 55lb injectors

This engine revs to 5500 clean w/NO shortage of air (6 inches of open element Frams), just not tons of upper RPM torque because of the cam, but low-end is REAL NICE and highway mileage is incredible. These are the engine/suspension specs for my Jeep Wrangler, by the way. Thirdgen in my garage getting tubbed for Mickey T N-50’s. This engine will go in the Thirdgen, when suspension/tubbing/axle narrowing is done… Then. bigger and better engine (502cid ???) for the Wrangler!!!