I have personally noticed that people use as many as they have engine space to allow. TO ME, it would seem that 2 or more would be better than one. Using two smaller ones you're not having to turn one large impeller as hard, could spool up more RPMs. I noticed this especially in the Diesel field, when Cat came out w/ the twin turbo ACERT engine and completely blew away all the other Diesel engines. THE DOWNFALL THOUGH was they were in parallel, so if one blew, you HAD to replace them both..... I've heard suggestions for a cheap turbo setup was to find 2 2.2/2.5 Mopar turbos and run them.....
twins are more to help lag response, two smaller are easier to push than one big one. if i go turbo im going for a bigger one. i think you would be better off with a large single. like the thumper 100-110.
The 2.2 turbos are way too small for a big block unless you use four of them, which in my opinion would be ridiculous. The biggest motor I'd use the turbos from a 2.2 on a 318 and that would still need two of them. And as far as it being easier for the motor to turn two small turbos than a single big turbo it's exactly true. If you think about it if you were going to run two turbos that put out the same cfm as a big one you don't really gain any faster spool. You might be using turbos half the size but you're also only using have the motor to turn it. Also faster rpm on the turbos don't mean more power. The faster the turbo spins the more heat it generates making your intake air hotter which would make the air less dense and make the engine more prone to detonate. So it would be better to find a turbo that would be able to boost a little more than you want it to so you're not maxing out the turbo. As far as if it would be better to run a single or twin turbo set up I would lean toward twin. The reason would be for the cost of the turbos. If you could pick up a couple of turbos off the Rams cummings engine you could boost up to 10psi on a 440 that's not going to do more than 6500 rpm. And even though it can boost up to 10psi I'd suggest boosting 8psi. And thoses turbos would be a lot cheaper than going out and paying a grand a piece for something aftermarket.
Turbochargers are dear to my heart; I've been burning down motors with turbos for quite a few years now. With the advent of EFI the turbocharger has really matured and, in fact, dominated the dynos with huge horsepower and torque figures with relatively small engines. My current build that these folks on this forum have been a help with is a twin turbocharged hemi E-Body. The build should produce in excess of 1200 hp and over 1000 lb ft torque reliably.
If you are building for the street twin turbochargers are prefered due to the fast spool and streetable torque production the smaller turbine will give. If for the track you can opt for twins or now they are building huge huffers like this one on the dyno http://videos.streetfire.net/hottestvideos/1/9AB8E11C-B2B7-4D34-A23B-22272D9A953D.htm. Anyway you look at it EFI is pretty much manditory to manage the potential of the new turbochargers.
Like anything else the turbocharger is an integral part of the engine build. First what is the purpose and goal of the combination then do the math on the engine specifics (mass flow, desired inlet pressure, temperatures, and on and on) which will get you in the ball park on turbine and compressor sizing. I have a quick and dirty Excel calculator that I use for basic turbine and compressor sizing that I can send you; no problem. Probably the most important thing to do is to "bone up" on modern turbocharging; understand the compressor maps and how to calculate mass air flow for an engine and the specifics to tuning a forced induction fueling systems.
I like the Turbonetics and Garrett systems. Both companies now have ball bearing turbochargers which take turbocharging to the next level.
How hard would it be to build a twin turbo big block on propane? I know i would have to build headers but i was planning on it any way. I figured if i just left a stock 400 long block with low compression and put 8- 10lbs boost it would make up for the loss of switching to propane. Do propane carbs have the same problems as gasoline ones when they are under boost? Thanks.
Dont knock a carb for a forced induction application. Go to Turbomustangs.com and see why I say that . There are some over there building big numbers and idle like stock and have great street manners with a properly built carb. When I mean big numbers I mean 1200HP out of 302ci
Oh yea, no knocking the carbs I have a couple big power twin turbo toys that are draw through carb setups but injection takes turbocharging to the next level. Amazing throttle response, early torque delivery, turbo spoolup tricking, better fuel balance which means easier on parts, etc, etc. I would put a pic of my favorite old style draw through here but it is neither a car nor a Mopar; that would be unethical..
I would agree garrett and turbonetics being good. I don't know about garrett but the turbonetics ball bearing turbos are rebuildable. Last I heard the garrett bb turbos weren't rebuildable. The reason I made mention of the turbos from the ram cummings is because you could pick them up cheap. You could find guys selling them because they up graded to a bigger turbo. By the way the turbo they use on the rams are by Holset. If you want to check them out the model is hx35w. It has a T3 flange bolt pattern, so you wouldn't have to find a weird flange like the ford power stroke turbo. If you have the money go with a bb turbo. They spool up faster than the friction bearings(the standard). So you could run a bigger turbo and have it spool up like a smaller turbo. As far as carb or efi. Again if you have the money I'd suggest efi. You have so much more control with efi since you can tune everything from idle to wot. With a carb you'll get good power, but you'll probably run richer than you need to be while cruising. So what kind of power are you looking for? How much are you concerned with the cost of things? If you're on a budget like me, I've learned a lot of cheaper ways to build things like this.
Not really sure, had some bad valve train issues when it was in the car, then took it out to sort it out on the dyno and promptly kicked a rod out the side of the block doh Was making over 800 foot pounds at 4000 rpm on a very conservative set up.