n/a 8v mpfi

[john1320]

-toying with the idea of going MPFI on the 94 Shadow. My question is, has anyone done this in conjunction with a header or ported cast ex mani? If someone has, did i provide any benefit? I would imagine with the T1 style intake, the bottleneck at higher rpms at full tilt would be on the exaust side?

Thoughts...

[BadAssPerformance]

The FFV were MPFI, right?

[Vigo]

I would imagine with the T1 style intake, the bottleneck at higher rpms at full tilt would be on the exaust side?

No way.. the 1pc intake is WAY worse than the stock tbi exhaust manifold. The 1pc is a complete pos that just has a turbo covering for it most of the time.

A 2pc would be better, or a heavily modified 1pc.

[turbovanman²]

I would run the TBI header, custom one piece and the FFV computer, which I have for sale, ;), maybe a mild cam and have some fun.

[john1320]

No way.. the 1pc intake is WAY worse than the stock tbi exhaust manifold. The 1pc is a complete pos that just has a turbo covering for it most of the time.

A 2pc would be better, or a heavily modified 1pc.

In a perfect world of stock parts, i'd use the 2 pc in a heartbeat if i had a spare. Ok, so that's one strike against a header from Simon. So then why was a header even offered, when carbs and turbo 8v were still young? Surely people were using them with success...

---------- Post added at 10:30 PM ---------- Previous post was at 10:28 PM ----------


The FFV were MPFI, right?
From what i hear, yes. The holy unicorn of Jyard finds- but most if not all are gone now. QQ

[135sohc]

I scooped up a 2 piece just for this purpose... someday I'll make it happen...

[22mopar]

I had a 1991 MPFI spirit. I don't recall it being flex fuel. it was built in Mexico. I remember the vin starting with a 3

[turbovanman²]

In a perfect world of stock parts, i'd use the 2 pc in a heartbeat if i had a spare. Ok, so that's one strike against a header from Simon. So then why was a header even offered, when carbs and turbo 8v were still young? Surely people were using them with success...

Of course a header is the best bet but the TBI header isn't a bad piece for a stock cast POS. A header gets every last HP out, a TBI header won't but they are cheap. I don't see an issue with a one piece intake, they suck better than they blow, ;)


I had a 1991 MPFI spirit. I don't recall it being flex fuel. it was built in Mexico. I remember the vin starting with a 3

They got all the fun cars, :(

[contraption22]

I don't see the one-piece intake being a bottleneck on a stockish N/A 2.2. The long runners will probably be a benefit to torque down low. And what are we talking about here... 100hp, maybe 110?
As far as the long-tube header. It would benefit a race motor with high compression, big cam and modified intake, but isn't going to be a benefit at all in a DD car. I would stick with a TBI exhaust manifold.

[Vigo]

IIRC the flex fuel and mpfi mexican cars were rated at 110 hp.

I calculated my modded tbi setup in the aries to be 115 hp many years ago, and that thing was MAJORLY in need of afr tuning. I think you could reasonably expect to get 120-130 hp out of a stock tbi motor by putting an exhaust, a good intake setup, and the right tune on it.

The thing is, you CANT get a good intake setup on it with a stock 1pc. The tb (and the area where the neck squishes down) are only like ~46mm? Most modern 2.5s have a 60mm throttle body. The 1pc also has a terrible plenum design.. I agree the runners themselves are not a problem unless you want to move the power peak up.

Having looked at them both a fair amount, i dont see the 1pc being a big step up from the tbi manifold. Either one needs to be majorly modified to get major gains out of an n/a setup. The 1pc will give you a handful of hp and let you make power a few hundred rpm higher, but as a power upgrade it wouldnt be worth the effort of the swap unless you modified it first.

I think an equal length long tube header would be more useful if you had a big cam (for which you need that big intake), and not that great if you were running a stockish motor.

22mopar has built some high power n/a setups (mostly carb i think) , maybe he will post some helpful info.

[contraption22]

Most modern 2.5s have a 60mm throttle body.


You'd be hard pressed to find a modern 2.5L N/A engine advertised at less than 150-160hp. Most of them have multi-valve heads or powerbands higher in the RPM range that would require more airflow.

[john1320]

I don't see the one-piece intake being a bottleneck on a stockish N/A 2.2. The long runners will probably be a benefit to torque down low. And what are we talking about here... 100hp, maybe 110?
As far as the long-tube header. It would benefit a race motor with high compression, big cam and modified intake, but isn't going to be a benefit at all in a DD car. I would stick with a TBI exhaust manifold.

I was thinking along the lines of a better scavenging effect that they do provide. You Simon and Mike all agree that a cleaned-up stocker will do just fine- and it's already there, lol! I have to agree that being a street trim motor, an expensive header would be moot, even with aggressive timing.
Sometimes it helps to think this through with others out loud- you all save me before i create my own headaches/mistakes!
I will do my best to do before-after mpg measurements and dyno, if Evilcow and i can get this off the ground with a cal or FFV sbecII swap.
But that is for another thread..

[john1320]

Anyone recall the FFV advertised mpg? Spoke with MPG Mike at length, and realized there is still alot to be had on the TBI setup economy-wise. Decided to tank the project after much debate and feedback from everyone. I still like to discuss this topic, for others who may go though this swap. Contraption thank you for the reality check! Learned here it would be wiser (when the time comes) to pursue a 2.4 swap (n/a still), which can lean burn better and have the HP already there without hassle. A weld-on tab for the auto trans, MS management, and mounts are what I would need, correct?

[Vigo]

I have heard of people getting 36 mpg on the highway with stock 2.5 tbi/5spd. I only ever cracked low 30s but my normal highway speed is 75-85. I did a test with my caravan when it was 2.5 tbi/5spd and got 33mpg @ 55 for a long distance so im sure i could have gotten high 30s with my aries (when it was tbi) if i had ever had it in proper tune and driven slowly.

UnaClocker on TD built an n/a 2.2 5spd rampage with a 1pc, running megasquirt, that he claimed got 42 mpg highway. But then again, GLHNSLHT2 also claimed to get 42mpg from a 2.2/5spd t2 daytona just by fooling the computer with the simulated narrowband output of a wideband.

In any case it seems 36-42 should be possible with some effort.

[turbovanman²]

Looks like about 26mpg-

http://alternativefuels10.tpub.com/m85emis/m85emis0016.htm

[john1320]

Ok thats VERY encouraging! I know there's more in there. Right now only gets av of 29mpg mixed driving. this is with mixed old tires, bad idle control (too high) and no tune. 33s right around the corner! It's an auto trans btw :( The price was right so I snagged it fast ($800) about 3 months ago. We are planning to do special plugs, dist ozone feedback mod, interceptor and cal-cat installs. Ordered gauge pillar pod for vacc and oil press gauges, i hate not seeing vacuum (need it for interceptor) and hate oil press dummy lights..

---------- Post added at 09:57 PM ---------- Previous post was at 09:52 PM ----------


Looks like about 26mpg-

http://alternativefuels10.tpub.com/m85emis/m85emis0016.htm

:D:D:D:clap::p:p:yuck: What a joke and a let-down, sheesh. Leave it to Simon to break my bubble- you bastard! Naaah just kidding, i would have never found that info. I still think 16v 2.4 will go in after motor dies.. god that might be a long time. Has 260k on it but purrs...

[turbovanman²]

Anytime, :nod:

2.4 n/a would be fun.

[Sundance 6g72]

2.4 N/A ftw

anyways, if you can get hold of a 2pc intake, do it. 1pc is a joke


its a 2.2 right? the 3.0 comes with a 46mm throttle body (or close to that) and a plenum that has a bunch of divets and a big divider in it. only made 141crank hp with it.


give the 3.0 a 52mm throttle body and port out the plenum and you see instant horsepower and torque improvements all over the rpm range. why would the 2.2 be any different? turbo guys like to hide the intakes bad flow with more boost.. which is fine, but you dont get that choice.


as far as exhaust goes, did i rear correctly the other day that the stock tube header on a sohc 2.0 fits a 2.2 head?

[Vigo]

The reason the 3.0 responds so well to a larger throttle body is because the stock one is way too small for the rest of the top end setup. I dont think that's true on the stock 8v top end. Also the sohc neon exhaust manifold definitely WILL not work on the 2.2. Port shapes and the flange are totally different.

But the 1pc is definitely a joke. I never knew how bad it was until i cut one open myself. For some reason seeing the pictures didnt have the same effect as seeing it in person.. i was shocked. lol.

[Sundance 6g72]

the throttle body opening is sooooooooo small :/

[Vigo]

Yeah, and the runner entry and plenum design is fugging horrendous. The runners themselves arent that bad unless you're comparing them to a 2pc.. lol

[john1320]

the throttle body opening is sooooooooo small :/
Not an issue with a stock 2.2, not even close to being a cork

[Vigo]

Yeah i think the real issue is the runner entry. It's so bad that improving it probably starts making power at a very low rpm. I think glhnslht2 has talked about his experiences there multiples times.

[Sundance 6g72]

has anyone ever ran mpi on a NA 8valve with a ported head, header, and a good intake before? i think that would be a fun project

[135sohc]

has anyone ever ran mpi on a NA 8valve with a ported head, header, and a good intake before? i think that would be a fun project

I dont think so... Everyone just goes all the way and does the turbocharger when upgrading from TBI/carb. I bought a two piece intake and have been gathering up parts for such a build just to do something different but its like number 123823834834534 on my list of things to do now.