tfreer85 Posted November 7, 2004 Share Posted November 7, 2004 Okay, I've got my 350 Chevy SBC that I'm rebuilding. I have nice performance cam with duration at .50 being 224 and 281 at .00. The compression ratio will be up around 10.1:1 with the new "beehive" springs and roller rocker arms. I'm running stock 64cc heads and have come down to the deciscion of fuel injection or carb. Eventually I'd like to do a remote mounted Twin Turbo system putting out small boost levels. The carb that i'm looking at is a 750cfm double pumper and was wondering if that would be sufficient enough to supply fuel for the turbos. Also with the TPI off of early 90's camaro's I've heard cannort handle camshafts with high durations, therefore having the added cost of recalibrating the computer. Also I don't know a single thing about wiring systems, therefore causing a negative mark for the TPI. Any feedback would be appreciated. Please let me know your pro's and con's and what you think of my system. Quote Link to comment Share on other sites More sharing options...
jonzer12 Posted November 7, 2004 Share Posted November 7, 2004 I am not sure what u mean by remote twin turbo system but 10:1 is a bit high for that. And also if you only plan on running small levels of boost why go twin turbo? In todays world I see no real advantage of trying to mix turbos with carbs. Wiring can be a pain but with the amount of information and knowledgeable people on this board alone you can't fail. I would personally go EFI if boost is involved. TPI is a great and easily available EFI system for SBC but it is not ideal for a sports car. High rpm and TPI don't mix and the whole system is designed to build lower to mid range torque in stock trim. Not all that important in a small light Z. If you just want to get the car moving I would just use your carb. Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted November 7, 2004 Share Posted November 7, 2004 First off I have a bias. I love my tpi for the big bags of torque down low. The tpi is a great platform for boosting, either TC or SC. The long intake runners that are reponsible for that great low rpm torque also rob the motor of high end power. Add boost and you have the best of both worlds. As far as reprogramming the ECM, you will have to do that anyways if you add boost. And you have options: get a PROM burner and use the stock ECM or go with any of the aftermarket engine management systems currently on the market, or buy or build a Megasquirt DIY system for a low buck alternative. Either way there is a learning curve you will need to traverse. IMHO it is well worth it. Turbo Meister, a member here, has a cool sbc twin turbo/carb setup in his Z. Very fast! Very cool! But even he has told others when asked to go EFI. In the end tuning will be much easier and much more precise. Quote Link to comment Share on other sites More sharing options...
Guest Magnum Rockwilder Posted November 7, 2004 Share Posted November 7, 2004 I have an article in Hot Rod that would help you immensely. It says that TPI is only good for engines <300hp, and once you reach that point a carb is best. TPI motors can't handle a big cam, and a big cam = big power. A carb is simpler, cheaper, more flexible, and can be tuned to produce peak power much easier than FI. Quote Link to comment Share on other sites More sharing options...
tfreer85 Posted November 7, 2004 Author Share Posted November 7, 2004 The remote mounted Twin turbo system can be found by looking up STS Turbo in google. However I've heard the the Tuned Port Injection can handle higher horsepowe and that it is the Throttle Body Injection which cannot. My main goal is to do some major street pounding with occasional drag racing. Therefore I'm going with the 700RE tranny just for my long commute to and from work. One of you has said that a carb is easier to tune and the other said the TPI was easier to tune. Which one is it? And if I do eventually turbo it will the carb be able to keep up? Sorry if this is pretty much a repeat of the last question. Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted November 8, 2004 Share Posted November 8, 2004 One of you has said that a carb is easier to tune and the other said the TPI was easier to tune. Which one is it? And if I do eventually turbo it will the carb be able to keep up? Fuel injection is easier to "tune" for turbos for street use. Turbos don't need a radical cam to make power. My Twin Turbo 383 Chevy in a 72 Z has so much torque I can't hook up with 12" wide Hoosier Quick Time Pros. However, my 750 Holley DP has to be jetted very rich at low rpms in order to flow sufficient fuel to satisfy the turbos at Wide-Open-Throttle. So cruising at anything below 30 mph in the neighborhood does not make for a responsive vehicle. Of course, it will break loose the rear tires when I floor it at 70 mph on the freeway. Anyway, with the right turbo set-up TPI and a mild cam will give you more power than the tires of your Z can handle. Hanns Quote Link to comment Share on other sites More sharing options...
tfreer85 Posted November 8, 2004 Author Share Posted November 8, 2004 Turbo, would I be able to see the beuaty of yours that evey I look is referred to. and you only running a 750cfm carb? Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted November 9, 2004 Share Posted November 9, 2004 and you only running a 750cfm carb? The 750 is plenty big for turbo use because air is being forced into the engine. The engine is not dependent on atmospheric pressure for airflow under boost and if jetting is sufficient(also fuel pump, & etc.) this carb can deliver plenty of fuel at WOT. FI can still give you better all-around-driveability but I had this carb --sooo. Hanns Quote Link to comment Share on other sites More sharing options...
tfreer85 Posted November 9, 2004 Author Share Posted November 9, 2004 What size is your fuel pump. my current and new one is a 110gph at 8psi, will that be sufficient? And also does a double pumper carb help out in the aspect of fuel delivery Quote Link to comment Share on other sites More sharing options...
Turbo Meister Posted November 10, 2004 Share Posted November 10, 2004 What size is your fuel pump. my current and new one is a 110gph at 8psi, will that be sufficient? And also does a double pumper carb help out in the aspect of fuel delivery I'm using an Aeromotive A1000, which is barely enough for my TT383. But it can provide up to 45psi. I dont think your pump is powerful enough for a Turbo V8. It depends on how much boost you will generate. If your carb needs 7psi fuel naturally aspirated and you have 15 psi boost then the pump must push 22 psi fuel to the carb. With 8psi boost and your fuel pump, the boost pressure will keep fuel from entering the carb fuel bowls and you are not going anywhere. I started with a Holley 160gph competition geroter fuel pump which was set at 15psi. It was not able to supply enough fuel at 10psi boost, causing my Z to drain the carb dry halfway down the dragstrip. I think the double pumper carbs are better than vacuum activated secondary carbs because you dont have to worry about sealing and pressurizing their diaphragms. Hanns Quote Link to comment Share on other sites More sharing options...
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