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importracer689
Apprentece
USA
8 Posts |
 Posted - Mar 17 2007 : 02:36:06 AM
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okay,
I've got an 88 5 speed vert with a new dealer installed low mileage 13b. I want to turbo it, in a quirky way. I want to install a remote mounted turbo, preferably where the catalytic converter is. I intend to run around 6 lbs of boost, and run a small intercooler.
My plans are as follows-
stock jspec sr20det turbo (t25 internally wastegated at 8lbs)
walbro or fd pump in stock tank
boost referenced adjustable FPR
S-AFC
some sort of blow off valve, adjusted to only hold around 6 psi so it will bleed ezcess boost generated by the turbo.
Questions-not sure if i will need to upgrade injectors, or if the S-AFC, fpr, and new pump will handle the low boost i intend to run. |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Mar 18 2007 : 10:49:49 AM
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Good luck with that. The turbo is VERY small for a 13B but I don't know how it will react being mounted after the cat.
You don't need a rising rate FPR if you are going to run the S-AFC. You'll need to upgrade the fuel pump and run upgraded injectors (4 x 550CC should be fine for you).
You're going to see a lot of lag with this setup. Don't let anyone convince you otherwise. |
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importracer689
Apprentece
USA
8 Posts |
Posted - Mar 18 2007 : 11:29:00 AM
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Thanks AAron.
Why is that turbo too small for a 13b. I was figuring that if it will boost an sr20 to around 10 lbs, or one side of a 300zx motor , it should have no problem boosting a rotary at low boost. How much lag do you think i will see? i was poking around junkyard turbo's remote section and there are a lot of remote turbos, and i dont believe they are experiencing much lag. ? thanks for the quick reply, keep them coming.
mark |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Mar 20 2007 : 09:28:19 AM
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Look at the size of the stock HT-18 and you'll see the difference. It's a very large T3 style with a 0.89 hotside. Search the RX-7 Forum for "hitachi compressor map" and compare it to the compressor map of the T25. You can also search for "T25" as well and see what others say. You underestimate how much air a 13B flows, especially the high compression 6 port.
As for remote mounting, there is lag. Every example I've seen has made very little boost in 1st gear and at low RPM. Most people don't notice because they do this to big V8s with loads of low end, or simply don't have anything to compare it to. |
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importracer689
Apprentece
USA
8 Posts |
Posted - Mar 20 2007 : 11:12:37 PM
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hey aaron. i spent some time reading through your site and you my friend are my kind of man. . i have done several similar things over the years. anyway
i have changed my ideas after looking up under the car.
I bought the turbo (off of a 300zx, stamped garret m24, with an a/r of 48. my buddy's sr20det has an ar of 50 on an upgraded turbo, and his stock was 48 as well i believe.
I got up under it and poked around and have decided to make/have a flange made to mount the turbo on the outlet of the stock manifold instead of super remotely. I believe this will work pretty well, and there is plenty of clearance. i also believe that the stock cast downpipe from the 300zx will work out pretty well. I do think that i will have to run an external wastegate, which hopefully i can work into my flange.
My thoughts at the moment are, using the flange that bolts onto the stock manifold, getting it welded/mated to a flat turbo flange, possibly including space for a wastegate mount.
how do you think that sounds? |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Mar 21 2007 : 10:22:52 AM
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That turbo is still too small. If you are talking about the exhaust side, 0.48 is tiny. The S4 turbo has a 0.89 exhaust side, the S5 turbo has a 1.0 exhuast side. This should give you an idea of low large the stock turbos actually are. The compressor wheel is something like 62 or 57MM. It's a BIG turbo for a stock unit. Most of the small piston engines use turbos that are way to small for a rotary.
If you are just looking to do a minor upgrade and not make huge power, look at using the stock S5 turbo from the RX-7. It will do about 260-275 to the wheels.
I don't think you'll find enough space to mount the turbo to the outlet of the manifold and have enough clearance to keep it level and provide the necessary plumbing. Either use an exhaust spacer and the stock manifold, make a new manifold, or swap on the TII intake so you can bolt the turbo directly to the block.
I also noticed something in your first post...BOVs don't control boost. Wastegates do. |
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my 88 vert ideas
