Mister Twister
Well-Known Member
Let's say the turbo I mount under hood gives me 150HP The question is, if I take the turbo and mount it where the muffler is now, around how much loss of HP would happen if any Don? 8)
How much loss for rear mount turbo?
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Backtobasics
Well-Known Member
Critical elements here are turbo sizing, and heat itself.
Rear mount turbo setups usually require a slightly smaller exhaust side, because the exhaust gases lose heat and thereby volume as the exhaust cools down the exhaust system.
Said another way, the smaller hot side of the turbo will require less exhaust flow to spool it. Since the exhaust cools and contracts, a smaller housing will react quicker, where the larger housing that you would use in a front mount system would have lag, and slow response time.
Rear mount turbo setups usually require a slightly smaller exhaust side, because the exhaust gases lose heat and thereby volume as the exhaust cools down the exhaust system.
Said another way, the smaller hot side of the turbo will require less exhaust flow to spool it. Since the exhaust cools and contracts, a smaller housing will react quicker, where the larger housing that you would use in a front mount system would have lag, and slow response time.
turbodart68
Well-Known Member
If you are using the same turbo, then the power would be similar. The draw back would be the extra time it would take to fill and pressurize both the exhaust and intake tracts since the will have more volume. In a street car it would probably work just fine, in a race car it could be frustrating. Remember "lag time is the moment when your opponent thinks he's winning"
bad440
everything,all the time..
was thinking about a rear mount turbo for my dart.any ideas?fuel cell in trunk.turbo where tank used to be.mine would have to be a blow thru.opinions please.twins rear mounted?I really like the turbo idea.every dart i have seen turbocharged has manual steering.damn my engine might be for sale if i could find a decent way to tackle this one.
Super T
Thisfieldistooshort
Say you're pushing 350cfm w/ the turbo. In a 3" pipe, at 15' of length with two 45 degree bends and one 90 degree bend, you're losing 14"w.c. of pressure, or about 0.5 PSI. At 400 cfm, you're about 0.7 PSI. 350 CFM in a 2.5" pipe, you're losing 1.3 PSI. (This is all estimated - the quality of your welds, smoothness of your bends, pipe material, exact length and routing, etc. will all have a huge impact).
It's not a ton, but if you're talking 6psi, that's 10% gone to friction, and noise, and weight...
It's not a ton, but if you're talking 6psi, that's 10% gone to friction, and noise, and weight...
On a side note, you also have to keep in mind that you are going to need much more piping and if it is a street car, you are probably going to want to ensure that the turbos don't end up being sprayed with water.
according to these guys turbo lag for rear mounted hair dryers is a myth. I remember watching them do a camaro on TV with the STS kit...
[ame="http://www.youtube.com/watch?v=rdjh3EY6shU&feature=related"]YouTube - STS Rear Mount Turbo Lag Demonstration[/ame]
[ame="http://www.youtube.com/watch?v=13cvNXQOCjo&feature=related"]YouTube - STS Turbo Corvette on 2 Guys Garage[/ame]
[ame="http://www.youtube.com/watch?v=rdjh3EY6shU&feature=related"]YouTube - STS Rear Mount Turbo Lag Demonstration[/ame]
[ame="http://www.youtube.com/watch?v=13cvNXQOCjo&feature=related"]YouTube - STS Turbo Corvette on 2 Guys Garage[/ame]
Mister Twister
Well-Known Member
Thanks for all the input on this. Looks like the question has been answered!!:snakeman:
turbodart68
Well-Known Member
Thats fairly impressive and I have heard on a street car that the response is good. I dont consider that response in the video to be a "myth" Even though it reaches zero instantly (which is true on all engines when you open the throttle) it takes it a few seconds to reach its max boost. Also one thing to note is that a Camaro of that vintage makes 275 hp and is using a small turbo which helps with lag. If you are going to go through all the trouble of turbo charging you might as well make some power, which will take a bigger turbo which will make lag time longer. One other note is that the Camaro in the video is a street car and all the lag demonstrations are on the freeway where the car is under power and has quite a bit of RPM already. When you are trying to launch a car on boost it is very tough to build boost against the torque converter at low RPM. My point is still the same I made earlier and people can skew a demonstration to show whatever result they want you to see, especially a video on the internet. Just my two cents for you to consider.
Excellent video of a rear-mounted turbo. He gets into the boost pretty good at 1 minute.
Museum car that had not been raced for a while so it was limited to 6k and 16#s of boost.
962C porsche single (large) turbo running thru dual intercoolers at front of engine compartment.
It does have a bit of lag. Mostly due to the size of the turbo. This is mid 80s technology.
And yes, it will make you wet your pants.
[ame="http://www.youtube.com/watch?v=h842NVgJC_s"]YouTube - Road Atlanta Porsche 962[/ame]
Museum car that had not been raced for a while so it was limited to 6k and 16#s of boost.
962C porsche single (large) turbo running thru dual intercoolers at front of engine compartment.
It does have a bit of lag. Mostly due to the size of the turbo. This is mid 80s technology.
And yes, it will make you wet your pants.
[ame="http://www.youtube.com/watch?v=h842NVgJC_s"]YouTube - Road Atlanta Porsche 962[/ame]
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