59hp increase with an exhaust?
#1
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59hp increase with an exhaust?
on rx7store.net there sayin that the racing beat will give you a 59(32%) increase in horsepower
The Turbo II High Performance Exhaust system incorporates a 3.15-inch (80mm) down pipe from the turbo outlet that mates to a presilencer section. From the head of the Y-pipe two 2.375-inch (60mm) pipes extend to the ceramic wool-packed 304-stainless steel rear main mufflers. The bolt-on exhaust system increases horsepower approximately 32% - a 59 HP increase on a 1987 Turbo II RX-7!
How could this even be possible?
The Turbo II High Performance Exhaust system incorporates a 3.15-inch (80mm) down pipe from the turbo outlet that mates to a presilencer section. From the head of the Y-pipe two 2.375-inch (60mm) pipes extend to the ceramic wool-packed 304-stainless steel rear main mufflers. The bolt-on exhaust system increases horsepower approximately 32% - a 59 HP increase on a 1987 Turbo II RX-7!
How could this even be possible?
#4
IIMMM BBAAACCKKK!!
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well, its been proven by racing beat and rx7store.... from a bone stock t2, just putting a turbo back exhaust on it DID (according to both of them) net around a 50hp gain...... the stock turbo exhaust is so restrictive to get it to pass emmisions.... and when an exhaust is put on, it opens the hell out of the exhaust, thus increasing boost levels....
#5
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http://racingbeat.com/resultset.asp?PartNumber=16425
"The REV TII High Performance Exhaust system reduces exhaust gas back-pressure significantly, thereby allowing the un-assisted turbo boost pressure to increase to 10-11 psi. Our Fuel Cut Controller (part No. 11570 or 11571) is required to prevent fuel cutoff to the rear rotor above the factory pre-set limit."
"The REV TII High Performance Exhaust system reduces exhaust gas back-pressure significantly, thereby allowing the un-assisted turbo boost pressure to increase to 10-11 psi. Our Fuel Cut Controller (part No. 11570 or 11571) is required to prevent fuel cutoff to the rear rotor above the factory pre-set limit."
Last edited by Juiceh; 01-21-07 at 05:17 PM.
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with the age of the car, its a great idea to replace the fuel pump and filters, and make sure the battery connections are in excellent shape before you put exhaust on.
10-11psi on a 20year old stock t2 = lean = popped engine.
10-11psi on a 20year old stock t2 = lean = popped engine.
#11
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It is not really all that loud, it has a presilencer which really helps.
I beleive this is probably the best upgrade for our cars. You will need to get a boost defender.
and YOU WILL NEED TO ADJUST FUEL
I have it on both my turbos and i love it!
I use the Rtec 2 wich lets me up my fuel but i used an S-AFC before and it worked just fine as well.
At the moment i have
Full Exhaust
4x 720 injectors
walbro
rtec 2
and i have a special cat that slips in place of the pre silencer to pass emmisions
I beleive this is probably the best upgrade for our cars. You will need to get a boost defender.
and YOU WILL NEED TO ADJUST FUEL
I have it on both my turbos and i love it!
I use the Rtec 2 wich lets me up my fuel but i used an S-AFC before and it worked just fine as well.
At the moment i have
Full Exhaust
4x 720 injectors
walbro
rtec 2
and i have a special cat that slips in place of the pre silencer to pass emmisions
#12
Upside-umop Racing
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RB exhaust is pretty loud on most occasions. Look some clips up on Youtube.com. There's all kinds of goofy kids with rx7s that like to record their car idling or revving. Have a look-see. On an rx7, the biggest gains of hp (for a stock car) are better intake and better output. Let it breath and it will run faster. It' like taking two new born babies and have one start smoking as early as possible and the other never smoke. In 20 years, who do you think will be more athletic? Wow, I really like anomolies. Is that the right word?
#14
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Originally Posted by Juiceh
http://racingbeat.com/resultset.asp?PartNumber=16425
"The REV TII High Performance Exhaust system reduces exhaust gas back-pressure significantly, thereby allowing the un-assisted turbo boost pressure to increase to 10-11 psi. Our Fuel Cut Controller (part No. 11570 or 11571) is required to prevent fuel cutoff to the rear rotor above the factory pre-set limit."
"The REV TII High Performance Exhaust system reduces exhaust gas back-pressure significantly, thereby allowing the un-assisted turbo boost pressure to increase to 10-11 psi. Our Fuel Cut Controller (part No. 11570 or 11571) is required to prevent fuel cutoff to the rear rotor above the factory pre-set limit."
I put this system on and I run 5.5psi all day long, but I did port my wastegate. So is the 10-11psi boost creep then?
#15
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Originally Posted by fossil_484
I put this system on and I run 5.5psi all day long, but I did port my wastegate. So is the 10-11psi boost creep then?
As for a video, look for the video of J-Rats's runs at the drag strip and on the dyno. I'm alomst certain that he is running that exhaust. Its still pretty damn quiet even on a nearly 500 hp car.
#20
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Except the stock wastegate is so small that it won't bleed enough boost with such a free flowing exhaust to keep you from overboosting. So be careful. And port your wastegate.
#21
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^^
Exactly right, the stock wastegate flap diameter is WAY to small for a free flowing exhaust. Therefore the wastegate cannot be considered properly working as it cannot regulate pressure to desired levels. Another way to help the wastegate do its job properly is to have a divorced wastegate downpipe, or even just to have a different back plate to let the wastegate extend further open as it doesn't really open that far in the first place. I believe on my s5 turbo, the wastegate opens approximately half an inch. I don't know how you expect that to bypass **** for exhaust ESPECIALLY on a rotary engine, where the exhaust gas pulses are a great deal stronger than a piston engine. AND SOOO I would suggest a good source of fuel control if you decide against porting the wastegate. My set-up with just a 3" downpipe and a 2.5 inch pipe eliminating the cat and the stock catback is pushing 8psi with my boost controller all the way down (straight wastegate) and when I unhooked the catback, I saw almost 11 psi on the turbo. So basically, unless you do some more serious mods, exhaust should be about last on your list as it can be quite dangerous to the health and longevity of the rotary engine on stock ems.
Just so everyone knows I have megasquirt, I don't care if I push 16psi on the turbo. I have the fuel and timing already adjusted... I'm pretty sure noone cares though lol
dpf22
Exactly right, the stock wastegate flap diameter is WAY to small for a free flowing exhaust. Therefore the wastegate cannot be considered properly working as it cannot regulate pressure to desired levels. Another way to help the wastegate do its job properly is to have a divorced wastegate downpipe, or even just to have a different back plate to let the wastegate extend further open as it doesn't really open that far in the first place. I believe on my s5 turbo, the wastegate opens approximately half an inch. I don't know how you expect that to bypass **** for exhaust ESPECIALLY on a rotary engine, where the exhaust gas pulses are a great deal stronger than a piston engine. AND SOOO I would suggest a good source of fuel control if you decide against porting the wastegate. My set-up with just a 3" downpipe and a 2.5 inch pipe eliminating the cat and the stock catback is pushing 8psi with my boost controller all the way down (straight wastegate) and when I unhooked the catback, I saw almost 11 psi on the turbo. So basically, unless you do some more serious mods, exhaust should be about last on your list as it can be quite dangerous to the health and longevity of the rotary engine on stock ems.
Just so everyone knows I have megasquirt, I don't care if I push 16psi on the turbo. I have the fuel and timing already adjusted... I'm pretty sure noone cares though lol
dpf22
#23
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Originally Posted by Steel
Except the stock wastegate is so small that it won't bleed enough boost with such a free flowing exhaust to keep you from overboosting. So be careful. And port your wastegate.
#24
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Originally Posted by dpf22
Another way to help the wastegate do its job properly is to have a divorced wastegate downpipe, or even just to have a different back plate to let the wastegate extend further open as it doesn't really open that far in the first place. I believe on my s5 turbo, the wastegate opens approximately half an inch. I don't know how you expect that to bypass **** for exhaust...
Divided downpipes are a good way to improve both wastegate flow and engine power, but you have to be careful with their design. If you put the hole for the wastegate pipe directly over the wastegate port, when the wastegate flap opens it'll partially block the hole, semi-defeating the purpose of having it.
Going back to RB's claims, the one important thing missing is exactly what their exhaust is being compared to. What was the condition of the (presumably) stock exhaust system on their test car? Was it brand new or did it have very clogged original cats? Did the power increase from the factory-quoted 180hp to 239hp, or was it actually only making only 160hp before the exhaust upgrade and 219hp after?
#25
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The flow of the wastegate gasses was the main reason I mentioned the divorced downpipe. I just didn't make that clear enough. I figured it wouldn't open much more though. Because seriously, flowing one way, then making what seems to me like a 180 degree turn, then a 90 out the downpipe seems like a lot of work. Giving it a more direct path from the wastegate to the exhuast system and out is much more efficient and I would imagine it would yield much better wastegate control.
dpf22
dpf22