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?

 

that would be nice. but highly doubtful, maybe 10 -15 horses with a full 3inch and dp depending on boost levels

 

Because it increases the boost several PSI.

If you're not careful your engine will go pop with that exhaust (keep a close eye on the AFRs).

 

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....

 

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."

 

is that with downpipe or not

 

with.

 

it is quite possible.

 

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.

 

how loud is this exhaust....does anyone have a clip of it?

 

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

 

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?

 

Analogies. An anomaly is an abnormality.

 

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?

 

Is that according to the stock gauge, or a reliable aftermarket one? Because you should be getting a good bit more boost than 5.5 with the REVTII system. And its not boost creep, its honest boost levels.

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.

 

5.5 is what I get with an aftermarket guage and my rtek 2. That matches roughly on the stock guage as well. As for the tone, it is awesome. A nice quiet roar that is distinctly rotary.

 

how is that. when you open up the restrictive exhaust you should push more boost should you not... if restriction is what holds the boost down, freeing it up should do like rb claims

 

holy alliteration batman!

 

Is the 5.5 lb wastegate spring doing it's job just right then? It would make sense if it only boosts to the wategate spring rating regardless of the free flowing exhaust. Am I mixed up somewhere?

 

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.

 

^^
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

 

i have a racing beat system is very quiet great piece of kit. and yeah you do get loads more power.

 

Was this for me or the first poster? If for me, then my wastegate is 30MM and with very smooth runner edges and larger flapper. Also grinded the flapper arm and backplate to allow more clearance. Having said that, then will the stock spring allow it to stay at stock boost levels with nicely ported wastegate?

 

This is common misconception based on assumtion rather than actually checking it. It's true that the flap does hit the stock backplate at full boost but, if you remove the backplate and apply air pressure to the wastegate actuator you'll see that the flap only opens ~1mm further than before. This is because the actuator has reached full stroke, i.e. its spring is fully compressed. Grinding a recess in the stock backplate or using a custom divided backplate makes virtually no difference to how far the flap opens.

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?

 

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