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Old 01-20-2005, 11:11 AM
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FI sources and limitations

I'm starting to load myself up with knowledge about FI systems. One of the biggest issues seems to be finding a decent intake manifold for these things! It seems that aftermarket fuel injection manifolds really just don't have a strong market, where do you find them? Also, what are the upper end limitations of something like a TPI setup? I wouldn't mind using one of those, but I wonder if it would have a hard time keeping up with the requirements of my bottom end? I just don't want to spend all this time and effort on EFI (eventually) and have the thing end up making 10 fewer horse than it did with a nice carb and aftermarket dual plane.

What are the upper end limitations on a factory TPI or other performance FI setup?

K

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Old 01-20-2005, 12:41 PM
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Both Edelbrock and Holley have EFI manifolds available. Both need porting work though based on our flow tests prior to installation. The last Edelbrock EFI intake we flowed for a 408 Ford small block build dropped 20 cfm with the intake bolted to the head. That's pretty aweful.

What I prefer to do is buy a Victor or Brodix standard intake and have the bungs welded in and fab up the mounts for the fuel rails.

A standard TPI is not rocketship when it comes to top end breathing. A complete Holley StealthRam would be a much better choice.
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Old 01-20-2005, 12:53 PM
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The biggest thing that limited the factory TPI, was its ability to flow air, and its runner length design. The TPI was originally designed for a 305, thus it doesn't flow enough air for a well built 350 or above. Its runner length is also almost 14 inches long (people forget that the runners actually cross from the left side of the manifold to feed the right cylinder in the intake itself). Because of these factors, you run out of power potential at about 4800 RPM on a factory TPI.

That said, there are many aftermarket manifolds that use the TPI components (fuel rails, sensors, etc) that help cure these limitations. The most popular among Corvette draggers, are the Super Ram, and Miniram. The miniram seems to be more popular among circle track and road course racers, as its powerband starts higher, and ends higher (due to its very short 3-4inch runner length).

The Super Ram (designed by Lingenfelter) is a mix of the stock TPI, and Miniram, and is actually closer in design to what they use today. It provides great torque, and extends the breathing ability and power potential into the higher 5000 range.

Holley also has a stealth ram which I have read makes pretty decent power, however you have to start with a certain TPI to be able to retain the components of it to use with the Stealth ram.

I think you'll find that once properly tuned, even a stock TPI can make as much power as a carb, and dual plane manifold, and give you a great boost in MPG. A carb will never be able to be as efficient as a FI, and lacks the ability to self tune. I find a lot of people complain about the FI maintenence, however I find I have to do less once its setup, that I ever had to do with a carb. Hard to beat a system, that for the most part is self-maintaining. There are things that can be done besides an aftermarket manifold to help power output (like throttle body size, injectors, tuning, etc). However, it will all depend on how hot a setup you put a stock TPI on. If you slap it on a 400hp setup, a stock TPI will probably lose you power. Id say once you start reaching the mid 300's you'll want to look at an aftermarket manifold. Knowing the kind of engine you'll want to put this on, Id start with an aftermarket manifold .

My recommendation, if you are going to go FI, is to get a complete TPI setup off ebay, and then use one of the aftermarket manifolds. Instead of going with a miniram or Superram, you can also use a bigger base manifold (A TPIS Bigmouth or Accel, or Edelbrock unit) as well as large tube runners and port the stock upper manifold (very easy to do).

I am not familiar with the other type of aftermarket FI units such as the ones TurboS10 and some of them are using. They seem to have great success with them.

I am currently running a fairly stock TPI on top of a 350 with some trickflow heads and absoltely love it. Plenty of torque and power until it hits the upper RPM's. However like I said, an aftermarket manifold will help cure this.
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Old 01-20-2005, 01:40 PM
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all of the aftermarket manifolds I've seen seem really aggressive! Isn't there anything more conservative than 1000cfm tunnel ram available?

K
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Old 01-20-2005, 03:21 PM
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http://www.edelbrock.com/automotive/man_sbchev.html

About 3/4 of the way down you'll see the highflow runners and manifold. Nothing too extreme, it will just allow more airflow for a higher Cubin inch engine and extend the RPM range.

This is a decent article too.

http://www.chevyhiperformance.com/te...858/index.html

It has the Superram as one of the last pictures. The throttle body choice is up to you. You dont have to use their 1000cfm throttle body. Most guys using the superram use the 52mm body. About 4mm larger than stock.

Came across this. Havent looked it over much but might provide some interesting numbers. The background makes it hard to read though.

http://www.geocities.com/MotorCity/7610/dyno.htm

This page shows the Miniram. It can be picked up for around 900 bucks. http://www.ws6transam.org/mr385.htm. Its more a top end higher RPM HP maker than the others.

The most mild being the Edelbrock parts and the mini ram probably being the most wild. There are other systems than these but these are the only ones I am familiar with.
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Old 01-20-2005, 06:26 PM
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This should do it for you KF , except a lighter car.
http://www.kinsler.com/i_manifolds.htm
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Old 01-20-2005, 07:46 PM
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It seems like a guy could make a pretty nice setup using one of Edelbrocks 2-4 low rise intakes and a couple of GM 305 TB's mounted on top rather cheap.

If a person was good enough to manipulate the stock brain into another/lower fuel curve it could also be used. Would anybody here know how to do that?
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Old 01-20-2005, 09:03 PM
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The two fours idea would be easy with a DIY system since they are an open book on the tuning.

Killer, I would suggest that you look to an aftermarket source for a manifold. I gave $1200 for my proflo before modification. That is not too bad considering it included fuel pump and everything. For your engine it would bolt on and run perfect. There is a very nice holley system on ebay right now for around $1600. The stock parts limitation have been made clear.

As far as the manifold design, the Victor style by edlebrock or the Holley would be perfect for your engine. As for the 1000cfm TB, you are in the carb frame of mind. A large carb does not negatively effect performance like a 1000cfm carb would. With EFI, you are not relying on signal to the carb fuel circuit for fueling. All you really get is something with a touchy throttle if the TB is a little large.

Chris
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Old 01-20-2005, 09:20 PM
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There seems to be very little in-between with this equipment. You have 1000CFM throttle bodies that seem to be pretty standard equipment on everything that is sold. Carb or not, I don't need that kind of flow, I'm sure of it. 750 CFM on my carb right now is wet flow, dry flow, theoretically, I should need even less. Fewer of those cubic feet are being taken up by fuel, its pure atmospheric content running through the pipes!

So it seems, also, that there are some aftermarket upgrades for the TPI, which seem like the street-guy's stuff. Then the next step up are these insane, dual quad, ram style manifolds that you know aren't going to flow crap for velocity on the bottom end of things. So is an upgraded TPI my best bet?

K
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Old 01-20-2005, 09:24 PM
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You just gotta get that carb thinking out of your head on TB size. It will not hurt a thing and the manifold is WAY better than the oe TPI type stuff. Start pricing the upgrades for the TPI stuff and you will find that a used edlebrock or holley is much more affordable. Been there and done that.

Chris
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Old 01-20-2005, 09:34 PM
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so a proflow is by best bet? WHat is the analogous holley unit called?

K
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Old 01-20-2005, 09:47 PM
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Not sure on the Holley name.

I like the edelbrock system, but have never delt with the Holley. I just think if you are starting from scratch with the engine you have, there is no reason to get something that needs a bunch of upgrades to work well. But, that is just me. Each to his own.

I would do as much reading as you can to get a good grasp on EFI and clear your head of the carbureted cobwebs. Prepare yourself....you are about to be enlighted..... and probably frustrated as hell before it is over

Chris
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Old 01-20-2005, 10:01 PM
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dang dude, I can't keep up with you, I though you were just in the other forum talking about business, now you're over here doing the fast fingers thing about FI!

Yeah I went to boarders a couple weeks ago and spent about 50 bucks on EFI books. Wish I had more time and space to start playing with some...

Yeah, in my experience trying to get factory stuff to perform is lame. I'd definately go aftermarket on all this stuff.

It just sorta hit me the other day, that carburetors only use the variable of air speed to determine mixture, but michigan, almost unlike any other state, confounds all the unmeasured variables! We go regularly from 60-110% humidity, barametric pressure changes regularly, and temprature ranges from -40 all the way up to 110 degrees. SUmmers are humid and swampy. We need EFI.

K
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Old 01-20-2005, 10:17 PM
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Fingers a blazin

Speed density will keep the engine performing at its best all the time. With a carb you can be rich or lean without changing anything depending on the outside conditions. It is also nice how clean an engine runs on EFI.

BTW, 100% humidity is all you get.

Have fun with it.

Chris
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Old 01-20-2005, 10:31 PM
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oops, meant to type 100, my numbers typing skills suck.

K
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