TexasShark

Hey c.w.a.v-
Fevre threw ya under the bus :lol:. I understand you recently installed a TPI and I'm looking for a kit I can convert to my 350 (soon to be 388) without any hood clearance problems. Can ya give me a heads up on your experience?
:thumbs:


[Modified by TexasShark, 11:04 PM 7/18/2003]

Fevre

It is not actual a TPI per say, TPI stands for Tuned Port Injection and is GM's name for their multi port fuel injection system. Cookwithvette used a Holley multi port fuel injections system the although very similar in function as the GM TPI it does not look the same but is still a multi port fuel injection system. If you want the lok of the GM TPI you have to go with accel street ram or one of the other after marke companies designs.

That being said here is a ttt for ya!

PatsLs1vette

like chris said they both look completely different,it all depends on what your looking for,the setup cookswithvette has uses a regular air cleaner style injection with separate injectors for each cylinder where tpi has runners a plenum and a throttle body where the air cleaner mounts on the end of it,not on top.

SmokedTires

If your serious about going with a Holley EFI setup IM or Email me smokedtires@aol.com and I can give you a phone number who sells and has a lot of knowledge with the Commander 950 and if he doesn't know the answer to a C950 question, Doug Flynn of Holley probably will (they've both been working together helping eachother out for about 10 years).

I just bought the Commander 950 ECU, software, & wire harness. I could have gone to a major mail supplier and paid around the same, but I went with the service/ support since this is all new ground for me ;) .

BTW, Doug Flynn also runs a 388 stroked engine in his car with the Commander 950. He can probably get you a pretty good base map on your engine :yesnod: . Doug is HOlley's programmer who writes many of the EFI programs for different engines while on a dyno.

I too am building a 388 only going the destroke route :) . :cheers:


[Modified by SmokedTires, 8:34 PM 7/19/2003]

Cookwithvette

Hey man, no problem. As others have said it's not a tuned port style. It uses a massive single plane, airgap style manifold. That being said, I'm using the stock hood (see sig) and have about 3/8" clearance above the air cleaner. I'm sure other air cleaners will work but for now I'm stuck with the Edelbrock Pro-Flo (bicycle seat).

My experience with the setup will almost certainly be different form that of others. Personally, I think the manual is kind of poorly written for someone who is entirely new to EFI. It's kind of a quick start guide. It's informative but didn't help when I encountered trouble. But hey, that's what forums are for right? :lol:







It's only this Monday or Tuesday that I'm going to be able to get the fine tuning done so I don't have a lot of road time on it yet but initial driving impressions are good.




[Modified by Cookwithvette, 10:41 PM 7/19/2003]

TexasShark

Thanks for taking the time to reply :thumbs: . Did your kit come complete, or did you have to order seperate parts? I've seen systems similiar to yours (cleaner on top vs in front of a throttle body). I've never worked on anything that wasnt carburated, so I'm trying to learn as I go. Someone else will be doing the install, I'm just trying to get an idea of what others have had success (and failures) with. Hey, that's what forums are for, right?! :lol:

Fevre

My drop base air cleaner assembly gives me more hood clearence then that 'bike seat'. I bought one cuz I liked the look but it hit my hood when I put it down.

Cookwithvette

The kit came NEARLY complete. It does not come with

1. Hose. I went braides SS because it's easier for me to work with than steel hardline.

2. Distributor/ignition. Holley gives you the choice of what type of ignition to use. I went small cap computer controlled HEI. Got the distributor from Paceperformance and the coil from Summit. The wires to hook everything up can be a beeee-ach. I ended up getting them from a junkyard because the wire that supplys power to the coil and distributor is part of a vehicle's harness. I can guarantee you'll never get that connector at an auto parts store. There are many options for ignition though.

3. Throttle body bolts. Manual says to attach the throttle body using the "included" 4 bolts and washers. My kit had no such hardware.

4. Fuel pump relay. There are two manuals and they contradict each other on how to wire up the fuel pump. One says the pump included is okay to be run off power supplied by the computer, the other says use the line from the computer to activate a relay. I went with a relay for saftey's sake.

I think that's about all I had to add. Good luck! Be sure to let us know how things go. :cheers:


It is true that a drop base aircleaner will give you more clearance on top but the throttle linkage on this is kind of tall so I have to be mindful of clearance there too. I think it was Zwede who modified his linkage and air cleaner but he's undoubtably more skilled than me. I'm going to keep hunting for an aircleaner that fits (haven't thought about it much yet) and intend to seal off the air cleaner from the engine compartment having the engine feed entirely from the cowl induction hood.

Here's a pic of the linkage. It doesn't look like much at rest but at wide open it sticks up quite a bit.




[Modified by Cookwithvette, 2:01 PM 7/21/2003]

TexasShark

Was there any particular reason you went with an MPFI vs TPI? I'm not familiar enuff with the two to understand any plusses or minuses. I wouldn't expect any major performance differences and the TPI system I'm familiar with (throttle body/cleaner in front) would appear to give more clearance. Again, your time is really appreciated. :yesnod:


[Modified by TexasShark, 7:45 PM 7/21/2003]

zwede

TPI is GM's version of port injection. MPFI = Multi-port fuel injection, so TPI is a form of MPFI. The GM TPI is not a high performance unit. It was designed for 305 cui V8's and even on the 305 it is flow limited above 5000 rpm. On a 350 the power starts dropping at 4500. You can upgrade the runners but it will never have the high rpm power of a short-runner design.

Holley makes what is called the Stealth-Ram. Front fed like TPI, but much shorter runners. Similar to a LT1 induction from the late model camaro/firebird/vette. This one screams at high rpm and is a great setup.

Problem with front-fed is that the front of them is rather tall and tends to hit our sloping hoods. They can't lower the throttle body, as the thermostat housing is below it.

TexasShark

Yep- I knew the GM unit was designed for the 305, but I've heard there are a few ways to improve their performance. Plus, I'm looking for off the line power and torque (my 350's being stroked to 388). Hadn't considered the hood slope interfering with the air cleaner. I'd hope to eventually fab a system similiar to patsnitrovette and collect air from the front grills but that's secondary. The important thing is setting up the FI. Right now my baby is a conversation piece in my garage. Totally unacceptable. :steering: Thanks again, all of you have been a wealth of information. Once I'm up and running, I hope to see you and Budman around the Metro. :thumbs:

shawn_cake

Make sure you clean the gas tank - and use at least a full AN-10 line.
Also - get rid of the stock siphon tube and filter sock! Make sure you build an AN-10 siphon tube with an AN-10 bulhead fitting and a properly sized siphon tube. If you sitck with the stock stuff, you'll have fuel delivery problems with the C950 MPFI on a 3 Gen Vette. I speak from painful experience!

:cheers:

TexasShark

Thanks. Haven't completely settled on the Holley system yet, but fuel delivery has definatley been a consideration. I'll pass your tips on to my mechanic. :thumbs:

zwede

Take a look at my webpage for pictures of a tank I had built. It works great. I can run it down to fumes and have no problems with it sucking air. The stock tank would suck air in corners when less than 1/2 full!

I have to disagree on the 10AN line... Since the lines are pressurized you can move massive amounts of fuel through a standard 3/8" line (I think that is 6 or 8 AN???). I have no problems feeding my 454 through the stock 3/8" steel line. First time on the dyno I had the pulse widths too long and had air/fuel at 10:1 and the line was still able to feed it. A 500 hp 454 running 10:1 AFR at 6000 rpm is ALOT of fuel!

burners

I am using the stock air cleaner assembly on my '78 and it just clears the hood. I had to modify (dimple) the area where the throttle linkage is but everything works well.

Weird Science

Cook, I remember a post a while back where I think Holley told you not you use braided fuel line?? Was this ever resolved or did further research just tell you it would be ok?

TexasShark

Thanks for the info. Like I said, we're "considering" everything. I try to make a habit of not fixin' anything that don't need fixin'! But I appreciate any input from the forum members. Will go stock first, then if we have probs . . . :banghead:

Cookwithvette

Burners, Unfortunately my car came with bubba's Mega-drop base air cleaner. :lol: Thanks for the tip. Now I know where to start looking. :cheers:

Weird Science, What had happened was the Holley manual only listed steel hardline and EFI rated rubber hose as "the solution." I asked around and Doug Flynn says he always uses braided SS hose. http://www.chevytalk.org/threads/sho...b=5&o=&fpart=1
:cheers:

shawn_cake

If you are using the stock position siphon tube - you'll need AN-10.
If you have a custom tank with bottom sump like Zwede's you can get away with smaller fuel feed tubes. Remember - the external electric fuel pumps push fuel very well - unfortunately these pumps are very poor at pulling fuel -especially from a stock position siphon tube.

zwede

I see what you are saying now. Thanks for clarifying.