Rotary 914!, 200whp ; Prepping for Okteenerfest Options

[gabeurgelles]

I also wanted to try out the helmholtz chamber exhaust system, but since there is WAY too much math involved with that, i just made it adjustable to find the perfect chamber length and then just lock it.
Surprisingly this little chamber changes the tone of the exhaust drastically! The theory behind it being that the chamber will create pulses that will cancel out the unwanted frequencies of the exhaust tone. Normally used to eliminate drone.

[Andyrew]

Looks great! Do you have before and after clips?

[gabeurgelles]

Here is a clip of the new exhaust.


https://www.youtube.com/watch?v=V3x7qZJfIeU

[mgp4591]

With the engine running it almost sounds like a small, single cylinder motorcycle engine. But man, that TONE is just killer! That's really a great job and good idea to make the chamber adjustable until you've got it just right. Nice job!

[gabeurgelles]

With the engine running it almost sounds like a small, single cylinder motorcycle engine. But man, that TONE is just killer! That's really a great job and good idea to make the chamber adjustable until you've got it just right. Nice job!

Thank You! The motorcycle engine sound is what I was trying to go for

[gabeurgelles]

Well, the engine came out again and this time it took longer than expected. Pulled the engine out to finally eliminate the smoking on idle due to worn oil control rings and oil control ring springs. Once apart I realized that I should just replace everything on the motor that would give me any problems in the near future. After taking them to a very knowledgable rotary engine builder in my area, I was told that I needed new rotor housings! Definitely not an expected cost. Old school housings put me back almost $1,000. While newer generation housings were only about $300. The difference between the housings being that there is a groove cut in old school housings for the water jacket seals while newer ones have grooves on the intermediate plates. Now I could probably find a complete 86+ engine for just over 1k but the old school (Pre-85) make the most power and are built better. So I just had to keep my old school, now the issue was how to make newer housings without a groove work. There IS one guy in all of south florida that can cut grooves into the newer housings but he charges $400 per side. Two sides per rotor, two rotors per engine... Basically not worth it, so I found a way to do it myself.

I made a template of the seal groove and used that to make a router template. After 5 discouraging attempts I pulled the trigger and purchased some very good condition housings and cut some grooves into them. They came out PERFECT and I was ready to assemble. Then came the idea to port the engine even further. The port timing was already maxed out for a street engine but the runner could have been bigger, so I maxed those out too! Before this rebuild I took the car, not tuned or in perfect time, to the dyno. Made 165 whp and around 117 lb/ft with an a/f mixture under 10 (extremely rich). This was before the bigger ports, and once I get the mixture down and the timing correct I was told I can expect between 220-230 whp naturally aspirated.

As of today the engine is back together and in the car and broken in. I am in the re-tuning stages, trying to dial in the carburetion. The plan is to eventually ditch the Holley and go to a 48 DCOE Weber as I was told that this combo is amazing for the street/autox. Looking forward to some autocross within the next couple months and maybe even some HPDE and Homestead Speedway or Palm Beach.

[gabeurgelles]

https://www.youtube.com/watch?v=PUklupMBnRc

[jimkelly]

sounds so sweet (IMG:style_emoticons/default/smile.gif)

[RickS]

Absolutely amazing. What a sweet ride. Did you get rwh stats?

[gabeurgelles]

Absolutely amazing. What a sweet ride. Did you get rwh stats?

165 rwh and 117ft/lbs running extremely rich (a/f under 10). This was before the last rebuild, in which I ported the motor further and will fix the air/fuel mixture. Shooting for around 220 rwh on the next pull

[Bills914-4]

Absolutely amazing. What a sweet ride. Did you get rwh stats?

165 rwh and 117ft/lbs running extremely rich (a/f under 10). This was before the last rebuild, in which I ported the motor further and will fix the air/fuel mixture. Shooting for around 220 rwh on the next pull

Wow nice skills Gabe, I just read this post complete , I wasn't aware you did all this work
to the 914 back in Nov. when we met at cars & coffee , for some of you that don't know
this young man is still in High School , I wish I had half your skills when I was your age ,
I'm planning on going to cars & coffee this sat. feb 13th, hope to see you there.
take care Bill D.

PS were's this dyno place located & what do they charge, I need to find a new place to
test tune my 914 , thanks in advance

[vw505]

I have a 901 trans that has an adapter for a full size 13B fly wheel and clutch. I want to build a wide body car some day, or sell it.

[tygaboy]

If I ever get an electric car and there's an option for having it play an engine sound, I demand you sell me a sample of that dyno run! That is such a bad ass engine note!
(IMG:style_emoticons/default/aktion035.gif)
Good on you, great work.

[gabeurgelles]

Absolutely amazing. What a sweet ride. Did you get rwh stats?

165 rwh and 117ft/lbs running extremely rich (a/f under 10). This was before the last rebuild, in which I ported the motor further and will fix the air/fuel mixture. Shooting for around 220 rwh on the next pull

Wow nice skills Gabe, I just read this post complete , I wasn't aware you did all this work
to the 914 back in Nov. when we met at cars & coffee , for some of you that don't know
this young man is still in High School , I wish I had half your skills when I was your age ,
I'm planning on going to cars & coffee this sat. feb 13th, hope to see you there.
take care Bill D.

PS were's this dyno place located & what do they charge, I need to find a new place to
test tune my 914 , thanks in advance

Thanks Bill, the shop with the Dyno is RotaryWerks right by tamiami airport. They host Dyno days where you get three pulls for $35

[gabeurgelles]

So now it's time for suspension, I've been looking into my options but would like to get some opinions. The car is going to be used on the street (going to and from events) for autocross events (maybe some DE). Right now the front and rear shocks are gone, and have begun to leak. I was thinking about going bilstein sport shocks front and rear and running a 22mm torsion bar. I have a sway bar laying around that measures 20.8mm but I don't have the drop links to attach it so I have to find those. The rear springs are #180. Would this be a decent setup for autocross and occasional drivers education? Any suggestions would be appreciated.

[Andyrew]

I prefer koni yellows due to their adjustability.

22mm torsion bars are very stiff, you wouldnt need to run a sway bar with that combo and 180lb springs.

[gabeurgelles]

I prefer koni yellows due to their adjustability.

22mm torsion bars are very stiff, you wouldnt need to run a sway bar with that combo and 180lb springs.

Being adjustable is definitely a big bonus. What if I keep my stock torsion bar and use the sway bar?

[Andyrew]

Pretty common setup there to stay with the stock T bars or 19mm t bars and use a sway bar.

Shocks will help stiffen things up as well.

[tomrev]

Pretty common setup there to stay with the stock T bars or 19mm t bars and use a sway bar.

Shocks will help stiffen things up as well.

Very nice fab skills! Second the stock T bar sizes, and 180 rear springs. Good shocks will allow a lot of tuning, and keep it happy for both street and racing. Nice thing about the Bilsteins is the adjust. spring perch at a reasonable price in rear.

[gabeurgelles]

Well this last weekend I took the car to the dyno to see how much power this 13b could make. To be honest, I had no idea what kind of number to expect once tuned. I was hoping for 190hp, but wasnt really sure. The first pull right off the bat, untuned, was 181whp and about 120ft/lbs. After a couple more pulls and jet sizes later, the car was at 198whp and 129ft/lbs. Seeing this number made me determined to reach 200. With some small timing changes, I was able to achieve this. The final numbers were 200.44whp and 131.87ft/lbs at 9500rpm