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99gtt wrote:The turbo hits 15 psi at 4600 rpm.
99gtt wrote:The turbo hits 15 psi at 4600 rpm.
strx7 wrote:99gtt wrote:The turbo hits 15 psi at 4600 rpm.
I love statements like this, 'tis like saying "i know how long a piece of string is"
What gear is that in and is that on the flat or up a hill or what?
The reason i'm asking all the questions is it seems like a rather large exhuast side for a 2L 4cyl. It'd be more at home on a 6 cylinder. It'd definitly make use of a long runner, equal length type manifold to get the best results.
99gtt wrote:I havent driven the car since the other morning, so just took it for a drive tonight . In second gear on the flat it makes 10 psi at 3400 rpm and 15 psi at 3900, but it does not start really halling ass till 4600 . I am really happy with the turbo , it is exactly what i wanted. I prefer the power at the top end,and it still comes in a lot sooner than a vtec or vvti.
quote] I am just running stock cams but power delivery isnt much different than stock apart from a lot more punch. The stock turbo use to hit 10 psi at around 2900 rpm but still didnt pull till just on 4000 rpm .The 4600rpm power thing will be down to either a) its current state of tune or b) the cams.
What cams are you running? I have 264's in my GT-T engine, Its not mobile enough to find out what the power delivery is like yet.[/
strx7 wrote:sure you aren't confusing TWIN entry with TWIN scroll?
Series 4 rx7's run twin scroll, 1 entry larger than the other, this effectively gives 2 different A/R's for the exhuast housing. One entry has a different entry angle onto the turbine.
The exhuast housings you are showing are twin entry, they are simply divided housings. I play around with turbo's a bit, hence the questions, i aint a newb when it comes to turbo's
I was running a T04 P trim 1.15a/r divided housing with 60-1 compressore & 0.70 A/R housing on my RX7, 2nd gear at 2000rpm..... open the throttle and instant boost, gotta love secondary bridge ports
I'm about to turbo my JZN130 surf, using the turbo off my rx7 as a sizing guide. I have a 1.52 Divided exhuast housing which i might try on it as i think the 1.15a/r will be too responsive for what I want (that sounds dumb i know) But my surf is a beast, I cruise around town in 4th and 5th pulling 1200-1500rpm. And I dont want boost till 3000rpm or more in 3rd etc, I just want 150 extra HP for when I'm towing the boat, towing my race cars, push starting sprintcars and playing against unsuspecting goons on expressways, gotta love the look on peoples faces when you are toying with them at 180+kph in a SURF of all things.
Can you tell me about that new twin scroll turbo Garrett put out?
A twin scroll turbine housing uses dual side by side passages into the housing. When coupled with a pulse converter manifold that separates exhaust pulses as many crank degrees in the firing order as possible, a twin scroll or divided housing works to reduce lag, decrease exhaust manifold backpressure on the top end, reduce the potential for reversion, and increase fuel economy. The twin scroll is based off the same reasoning a tri-Y header uses: keep spent exhaust gases out of an adjacent cylinder drawing in fresh air. At high rpm on a turbo car, exhaust backpressure is usually significantly higher than atmospheric pressure, and often higher than intake manifold pressure as well. A divider between each of the two volutes allows the cylinders to expel the exhaust gases without it interfering with the fresh air for combustion. Since there are two openings, each a smaller overall volume than a single scroll design, the exhaust velocity of each pulse can be maintained. This also spins the impeller more easily because lag is a function of the scroll area. A single turbine housing opening isn't as efficient since cylinders on the exhaust stroke of the 4 stroke cycle contaminate the cylinders that are on overlap with exhaust gas. A conventional turbine housing is not as effective in using exhaust pulse energy to help spin the turbine up to speed as it does not exploit the energy contained in the pulses as well.
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