Hey Stinkfist, (1) I don't have a scanner so I can't post dyno's, pictures etc..Why don't you go to engine builders and look. (also do a search) you can see if I am "for real"..better yet post in the 3rd gen area and ask...(2) You have no reading comprehenssion. 28% was at the crank which is 23 rwhp. (3) Call racing beat and ask them for a dyno I'll bet they can provide one. (4) You obviously have zero experience with first gens. They have a thermal reactor and then 2 cats and the exhaust pipes are as thin as a drinking straw. (5) You also quote exhaust makes a big difference in a rotary engine, it's the same for any engine..No, a rotary engine gains more hp than a piston engine when the exhaust is freed up do to the pulse cycles inherent in a rotary. (6) You seem to be ignorant for some reason on this subject. You arn't educated enough to debating this issue.

 

Chris,

This is a really good point. However... let's do the math here. I was dynoing a 88 'vert. EVERY 86-88 I have ever seen dyno stock has been about 110 hp. Rotary Performance confirmed that number as being a good-running stock Series IV when we were there. The same day I dynod my car, there were 2 other FCs, an 87 (that was a former C stock SCCA autocross champion, from 2 years before- this car is IMMACULATE) and an 89 that wasn't running right- he only put down 100 at the wheels. The 87 (Identical to my 88 from a powertrain perspective when both were stock) put down 110. I put down 130 that day. My mods were a cone filter, and a 3" single exhaust WITH a high-flow 3" cat, and my 6-ports wired open. Wiring open the 6-ports does NOT make more power, they make exactly the same on the top end, and you lose low-end torque... but mine were not working properly so I just did the quick hack. A free-flowing exhaust with no cat would give a bit more, as would headers. Full duals (due to port timing/exhaust pulse tuning) produce a bit more.

Brad

 

Finally someone can end this.

 

Stinkfist, What do you have to say about Brads thread..? Here it is :". The 87 (Identical to my 88 from a powertrain perspective when both were stock) put down 110. I put down 130 that day. My mods were a cone filter, and a 3" single exhaust WITH a high-flow 3" cat, and my 6-ports wired open. Wiring open the 6-ports does NOT make more power, they make exactly the same on the top end, and you lose low-end torque... but mine were not working properly so I just did the quick hack. A free-flowing exhaust with no cat would give a bit more, as would headers. Full duals (due to port timing/exhaust pulse tuning) produce a bit more." ***********************************That is a 21% difference RUNNING A CAT..A straight pipe or silencer will yield less back pressure and greater (bigger) hp numbers. Good post Brad..

 

Hey, it's not impossible to have 30% gain over a bone stock with an OLD clogged up exhaust. It's a 30% gain over the peak HP rating that some of us have a problem with and most of you think it is possible. True, the dual set-up without cats will evacuate more exhaust but you can't create mega HP without significantly increasing intake charge. How many of you have done a backpressure test on a NEW stock set-up and then a race set-up? What is the difference between the two? Can anyone please tell me?

 

No, Those gains can be seen with new exhaust systems. The reason is emissions and the ability to pass them. The stock exhausts are extremely restrictive. It is also not just at peak. At 8000 rpm's on a stock exhaust vs a rotary engineering setup there was an 84% difference in hp.(after 7000 rpm the stock exhaust cars dyno dropped straight down, wheras the aftermarket exhaust car dropped but slightly. I have the dyno chart I just have to find it).

 

im stating facts, he didnt believe they got 28% increase on a FC with an exhaust system, he asked for a DYNO, we showed him, and now he doesnt believe it and says its bullshit.....dont tell me thats not gay and not flaming......

 

AbecX and wpgrexx, you have both been warned on the previous thread. STOP FLAMING. Warning #2. Next time it's a week ban.

Brad

 

28% rear wheel hp is believeable..
RWHP is the key to that sentence.. don't take 28% of 150... on a stock... 28% of RWHP is a lot less than 28% of Flywheel HP

 

We have heard rumors that the front running cars can put down 200-220 to the WHEELS!



-Ted

 

All it takes is $$$$$$$$$$$$$$$

 

Why? I don't care.

Actually, almost every quote I saw was at the wheels and I also said that in all of my post. The original quote from mazdatrix was at the wheels.


I don't like Racing beat's lack of customer service. If I have to buy anything made by RB I do so through Mazdatrix.


I own a Heavily moded one, have sold another and crew cheif for a race team that races IT7 (1st gen). I also help out sometimes with a friends EP first gen. I can't remember how many 12a's I've built.



None of mine have these.

So you mean to tell me that there is no piston engine on this planet that could gain more HP from a full exhaust mod than a rotary. WOW! you have done A LOT of research.

I did not say it was the same for any engine. I said "I know exhaust makes a big difference. It's not some rotary secret. it's true for any engine." Meaning that a free flowing exhaust will make more power on any engine. Not that a piston engine will gain as much as a rotary.



Not that I care what you think of me but just so you aren't making blind statements.

My education consist of 2 years of Mechanical Engineering at the University of South Alabama. I didn't graduate but I had to learn something in 2 years

8 completed ASE test. One more makes me a master technician.

Several Jaguar technical coarses. (I work on Jaguar's for a living)

Two years Being crew cheif of a front running IT7 car in the SCCA. 1st gen w/12a.

4 years owning and heavily modifing rx-7's

And other automotive jobs.



Now as far as the proof I asked for. Well it apears someone has suplied it and I must humbly eat my words. I WAS WRONG.

I do believe Mazdatrix. I know they are a reputable buisness.

However I assure you that the results they got are not the norm.

MMmmmm, crow is good,

Mike

 

Mike, (1) My point was your education based on first gens..I was correct. (2) The reason I told you to ask about my experience is you asked, remember..? (3) I do not do any business with racing beat for the same reason. (4) The exhaust stock did have a thermal reactor and two cats and that was my point (restrictive). (5) You quote " I was wrong". I knew this from the begining when you were calling B.S....Enjoy your crow...

 

Actually, if you take every fact presented here, Mazdatrix's claim was on a car in "good running condition" or words to that effect. I'm too tired to go back and find the actual quote. Their dyno sheet shows 100hp which has been accepted as less than perfect peak. Assuming the only problem with Mazdatrix's car was clogged exhaust, that is stil an 18hp gain, or 16.36% over a perfectly running stock N/A. No, it's not 28%, but it'w worth looking into. Understandably there are many cynics who believe businessmen (those people who make a living on nothing but rational thought) are all out to get them, personally. I am not speaking to this crowd. The advertised numbers were likely on the conservative side because there is nothing worse for a products sales figures, than to fall short of claims. Those who cry marketing gimmic, please audit an entry level marketing class at your local Community College. My H.S. marketing class (I graduated 4 years ago, so don't scream dumb kid) explained this much: word of mouth advertising for a good product that meets its claims will sell more units at less cost than all other forms of advertising combined. That being said, I'm unsubscribing from this thread, and avoiding any thread AbecX posts on. I do not care for irrational second-handers and looters. For an explanation of that comment read "The Fountain Head" and "Atlas Shrugged." I'll not be back to this thread.

 

Ever been to a dyno and have the operator ever ask you how much you think they will make?.. Especially one owned by a shop that just sold you a bunch of parts... Dyno results are not always true and can be alteredl, just open the valve on the ole' water brake, and low and behold, +50 hp on all the readings to get you comin back for more....
The G-tech, well when I first got it, I thought it was stupid, inaccurate and a waste of time, then Chris NG the guy I got it from gave me some operational pointers and I started getting better readins from it, still not completely convinced, I marked an exact 1/4 mile on a nearby highway just to see if its measurements were right, well what do you know, its exact in its 1/4 mile run and cut off, with distance and time... So when an FC runs a 18-19 second quarter mile, whick equates to about 50-65 hp dpending on the car, a bunch of fc owners get their knickers in a knot, how it can't be true, and there's no way and FC could only make 50 rwhp.. Well kiddies, physics doesn't lie.. Either the rx-7 wieghs more than what mazda says or the car has way less hp than what mazda says, so which is it, I personally wieghed my car at its 2790 with me in it.. One must remember as well, these cars are 14, 15, 16 years old, most fc's are borderline shitboxes, with enough repair done on them to just keep them on the road, they rated at 8.0 0-60 brand new in perfect condition which is slower than alot of modern pickup trucks, Mazda(probably at sea level with their best driver on a 45 degree day, with a exceptionally well tuned brand new car, with perfect functioning fuel system ) clicked off a 16.1 quarter mile.. which equates to about 115 hp , now considering that car used for their boasting numbers, now dip into reality to your average 15 year old FC with less than perfect conditions and yes 50 rwhp na's are the reality. Like it or not..
Now some guys are gonna say well hey but my car made 105 or 140 at the wheels, well if you consider that you cared enough to get your car dyno'd, its probably not stock, and probably not in the condition most n/a's on the road are in, if you care enough to be here in the forum, and on a dyno for 80 bucks an hour, you probably care enough to tune your car, and make some mods to increase power, and remember MR RX7 TT, I said your average NA, not your N/a or your best buddies, but the average N/a which mine was when I got it, and what others I know had when I met them.. and yes I am showing now 107 hp rwhp numbers and I am running my car down the 1/4 mile on friday where I fully know that I will run close to 16.7 at 80 mph, this is a well tuned (now) n/a with a header, catback, working sixth ports and 180,000 km's running 225/50/16's on it being run at 4000 ft of altitude with 80 + deg temps..
Am I embarrased that my car is a only a 107 hp, well no I still like the car, I have a TII on the go that should be 400+, I drive 475+ rwhp 4x4 around, so I get my power rushes other ways, I don't have to live in lala land when it comes to how much hp my n/a makes..
To many people throw around big hp numbers without actually realizing how much a hp is, and what it equates to work wise, I work with 50,75, 100,150, 200 etc hp electric motors all the time, you would be suprised how strong a 50 hp motor is and what it can do.. I really think some people are just to proud to admit that there are some real hurtin 7's out there...Max

 

In my 87 NA when I replaced the stock exhaust with a bonez high performance cat and a single N1. I went from running high 11's and the occational 12 in the 1/8th mile to running 10.0-10.2 in the 1/8th.

I have no idea what the HP gains were but the exhaust swap clearly had some significant gains. As were reflected in my times.

 

I think someone should tell this to those tornado guys before they all end up in jail. LOL

 

There are like 8 million posts on this subject and hardly any are spelling out any clear data. Here is my first hand expeirence with RB dual exhausts-

1983 12A mods- K&N air filter, electric fan, Bonez race pipe- no cats, walker performance muffler

Dynoed @ 89hp

With RB dual exhaust(only change) Dynoed @ 116hp

Stock usually dyno's around 70-75hp

So over the modded setup dual adds 30% more power.

Just for comparison my 84 GSL-SE with an 89 NA motor dynoed at 177hp to the wheels with bolt ons- Under drive pulley's, RB dual exhaust, electric fan, steel light flywheel, msd ignition, Cone filter, 6 ports removed, SDS stand alone efi system.

That works out to around 210 flywheel hp. Stock is 160. So there is another case of a 30%+ increase in power with just bolt ons, so dont say its not possible.

84 se dyno chart-
http://www.marx7.org/~slelievre/RX-7.../rx-7%20na.jpg

 

You can get horsepower on a dyno that won't necessarily be driveable on the street by tuning the car for the conditions there on the dyno - play with plugs, timing, other stuff. While I don't doubt Mazdatrix made 28% more HP on that car, it most certainly isn't typical.

That said, RX-7s are a totally different world than most other cars when it comes to exhaust tuning. I've seen stock 7s then went like scalded dogs after exhaust upgrades.

Opening the exhaust makes a ton more power on a rotary. If you've ever heard a rotary with headers and open exhaust, you know how much louder they are than most piston engines. The reason that 2nd gens are so relatively quiet is because the stock exhaust chokes them down to quiet levels...

 

omg not again........

 

damn nice #'s!

 

The thermal reactors are only on the pre-81 rotaries. They had a reactor and no cats. The 81-85s run 3 cats just like an NA second gen.

Go back to the FD section, where no one likes you there either.

 

ok i did some testing this weekend. i had to make my rex stock to pass new texas emmisions laws so i took off all my mods and made it stock with a paper filter element. i used my gtech and pulled off an 8.1 0 to 60 stock, then when all my parts were on(racepipe, catback, cone intake, msd ignition) i ran it again and pulled off a 7.03. regardless of how accurate gtech is that is a signifigant gain IMO. and i havent gotten headers and an safc yet yet. i need to run the 1/4 and get dyno'd so i can do before and after with my car stock and fully modified

 

if you half to bicth and whine about exhaust dont get it , unless you know nothing , dont buy the exhaust if you are not sure enought that you must bouther us!

 

"1st gens have thermal reactors and two cats?"


what r u smoking

only 79-80 had thermal reactors and the thermal reactors were used in place of a cat

also......

the specs ive seen only claim 146bhp@6500 rpm(1986)

take into account 20% driveline loss= 116.8 rwhp

28% of that= 32.4 rwhp gain

if it is all measured at the crank then....

146bhp x28%= 40.8 hp gain

now look at mazdatrixs car with a baseline of 98rwhp

98 x 28%= 27.4 hp gain

next you have to figure that this is a peak horsepower gain not a consistent gain throught the curve. that means at 1 precise point there is a 28% gain and at one point only most likely above the 6500rpm range. the rest of the curve only sees modest gains.....

so what am i trying to say with all this babble??????

just that think before you speak and some of you need to go to math class and some of you need to take reading comprehension...

as a disclaimer i am not claiming anything here just presenting mathematical facts for you to draw your own conclusion