silicone boy Posted October 7, 2003 Share Posted October 7, 2003 I have decided to take the plunge and add a couple of turbo's to my chevy motor (a 383). I might as well because the motor is out of the car. I know that some of you are considering the same thing. My chassis is about as prepped as I can get it, including stouter rear diff, brakes, suspension, and most recently, subframes and a rollbar (what a PITA-it's been a lot of tough and dirty work). My question is regarding type of turbocharger. Some have talked about using Garrett T03's that are found commonly in junkyards. They look like hairdryers to me. I'm not sure if they're big enough for a high horsepower V8. I was thinking about Garrett T04B's (especially since I already have one). Do you think this is appropriate? A couple of turbo calculators on the web say that a T25 would be the best match, but I think these are dinky as well. Sure, they'd spool up quickly, but that's not what is needed on a stroker V8. What are your thoughts? Quote Link to comment Share on other sites More sharing options...
yo2001 Posted October 7, 2003 Share Posted October 7, 2003 You could prolly use two nice size T04B's Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 7, 2003 Share Posted October 7, 2003 I checked out your web site, now I understand "silicone boy" Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 7, 2003 Share Posted October 7, 2003 Depends on how much HP you want to make. Twin T3s will easily support 500, twin hybrids like TO4Bs will support up to 700 or so. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted October 7, 2003 Share Posted October 7, 2003 T3 exhaust housings will be too small. TO4s are the answer. Tim Quote Link to comment Share on other sites More sharing options...
silicone boy Posted October 7, 2003 Author Share Posted October 7, 2003 Holy smokes! I never even realized that my website was accessible from here. Now you know why I always say: there's no replacement for displacement. Then again, a little bit of boost can't hurt. Quote Link to comment Share on other sites More sharing options...
awd92gsx Posted October 7, 2003 Share Posted October 7, 2003 Why not a single T66 or something like that? Quote Link to comment Share on other sites More sharing options...
DavyZ Posted October 7, 2003 Share Posted October 7, 2003 Silicone boy, I have discussed this topic in depth with ScottieGNZ and I am now convinced that bigger is not always better. Case in point, I figured about how much HP I wanted and then decided what turbo(s) I wanted for the engine. Getting back to "bigger is not better": the size of the turbos is deceiving, especially when you are smacked in the face by magazine cars with over-the-top turbo setups. Would you believe I am going for 500 too 550 HP on one T04E? Yep, no problem! And that is one turbo, Baby. Twin T04B's would be awesome and could give you much more power then you desire. I think you'll be fine. Remember that GN cars are making sick amounts of power on one, relatively stock turbo... I originally wanted to fab my own EFI system and all, but after calculating $$$ for everything, I realized that I am not a plastic surgeon and have to be more practical if I want my family to eat something other then the venerable PB&J every nite. So.....I decided that cheap EFI and a stout engine comes in the way of the Chevy LT1. I have the direction and the contacts to make this happen in due time. 500 HP will be easy, get reasonable gas mileage around the town with the dropped 8.5:1 compression pistons, yet fly under 8lbs of boost Good luck! Davy Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted October 7, 2003 Share Posted October 7, 2003 Silicone boy, what is the compression of your motor? Are you going to rebuild it with lower compression pistons, or leave it the way it is? What kind of boost can you make with a 10:1 engine? Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted October 7, 2003 Share Posted October 7, 2003 I thought that the LT! computer couldn't use a MAP sensor for boost. How will you control it? Quote Link to comment Share on other sites More sharing options...
silicone boy Posted October 8, 2003 Author Share Posted October 8, 2003 The compression is a little high because I'm using my original heads (AFR 195's that were shaved down to 64 cc's). With the dished pistons I got, that gives me a compression of 9.7:1 . My original pistons gave me a compression of 10.8:1, but I trashed one of them when I fired up my motor for the first time, not realizing that I dropped a bolt into one of the cylinders. That gave me the excuse to get the lower compression forged pistons. The compression of the new setup is a little high, but I hope I can prevent detonation with a good engine management system, a junkyard intercooler, and a $70 water injection setup I found on Ebay. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted October 8, 2003 Share Posted October 8, 2003 I thought that the LT! computer couldn't use a MAP sensor for boost. How will you control it? I believe if you change the sensor to a 2 bar, or 3 bar depending on boost levels, the LT1 PCM will handle it just fine. Tim Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted October 12, 2003 Share Posted October 12, 2003 I agree about the "Bigger is not always Better" cliche. A turbo's A/R ratio and Efficieincy is kind've like the relationship between your Intake Manifold Ports/Cyl.Head Intake Ports: providing SCR & DCR are not changed. The larger the Cross-Sectional Area of your Ports leading up to the Total Chamber Volume & Cyl.Volume you have-the longer your [PEAK] airflow velocity is delayed from surfacing till later in the rpm range: likewise, the larger your A/R Ratio the later that turbo will spool. The smaller your A/R Ratio the sooner the turbo will spool. On a normally aspirated engine you can delay the airflow velocity from peaking too soon by utilizing Intake Manifold Ports and Cylinder Head Intake Ports that are slightly larger than what you really need. This way torque will not max out at low rpms-your engine will likewise, not over power your car: because this airflow velocity is minimized at lower rpms your peak power will then surface at a later rpm when you really need it most. The A/R Ratio of a Turbo works in this same manner. You dont have to have "Big" anything to meet your objective when installing a turbo(s). What you need is the "Correct" something to meet that objective. Obtaining the correct size housing to turbine (A/R Ratio) will allow you to choose when you want your peak power (peak airflow velocity) to surface. If you plan on keeping your higher SCR then you will want a Turbo w/an A/R ratio that allows the turbo to spool up at mid to upper mid rpms as a HiPerf. 383 should make plenty of its own torque down low. If you do alter your SCR and go w/a lower SCR then you will also want an A/R ratio that compliments the lower SCR: as said before-all we are doing is manipulating the airflow velocity w/our modifications. If you have not purchased one or two turbo books then you really need to do so: read them till your brain hurts. Make sure you understand the math-no matter how long it takes you. Once you have done this then you wont have any problem reading turbo maps & choosing the correct turbo's. FWIW: I have both Corky Bell's and Hugh MacInnes (sp?) turbo books. I like Corky's book the best. Kevin, (Yea,Still an Inliner) Quote Link to comment Share on other sites More sharing options...
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