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2 Rotor Volkswagen Golf MK1

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Hi all,

after having a look at some great threads i decided to show you our project. We bought this car 3 years ago from a good friend who gave up with it as he ran out of money and time to go ahead with his car.

After the purchase, we first painted the car and gave it our "style". We did not make any big changes in 2015 because we wanted to see what the car is good for. After a lot of tuning the R-tech ECU by a friend of us, we were able to increase the best E.T. from 10.4@217 km/h to a 8.57@252 km/h at the end of the year 2015.

In 2016 we have switched to the Fueltech FT500 as the R-tech had some problems with datalogging and some outputs not working correct.

Unfortunately, our friend did not want to deal with the Fueltech and so we had to do everything on our own. We all know about cars but none of us has ever built an EFI. We just got into trouble and just did not get the car running properly. But ambitious as we were, we continued to do everything on our own. We fought through forums and tried to learn all the features of the rotary engine.

Nevertheless, we had only moderate success and by mid-2017 , 7 engines were blown up :-(

Only some examples

But then we finally made it and we succeeded. The car is now running a constant medium 8 seconds and so it was time to dare a major conversion.


This winter we have rebuilt everything to be able to drive with methanol instead of E85. We removed the intercooler, installed a boost pressure control with oxygen and increased the turbo from 76mm to 80mm. We also painted it new and gave him a new wrap for this year.

Mini Cooper water cooler fits perfect for us :-)

Boost control

The rebuilt turbo

The engine bay at the moment

And the car how it looks now.

I do not want to bore anyone and that's why i stop here now :-). Our first race will start in a week and maybe i will have good news afterwards ;-).

Only a few technical details from the car

- Volkswagen Golf MK1 ´79

- fulltube chassis

- 9inch Ford rear end with a 4-link and strange shocks and axels

- 2-speed powerglide transmission with a hughes performance 7inch pro mod converter ( 6500 rpm stall-speed )

- 13b cosmo engine

- large street ports, semi p-ports and race clearanced 9.0:1 rotors

- RX8 e-shaft

- automotive mechanical fuel pump

- E&J Throttle Body

- 8 x Bosch 210lbh injectors

- modified Borg Warner S400 turbocharger

- Fueltech FT500, 3 Lambda controllers

Hi Marc,

Fantastic stuff & it looks amazing! Just out of curiousity, what was the main cause of initial blown engines?



Nice proyect , well yes rotary is not the best plataform for learn to tune and even less in a max effort aplication like drag racing but it seems that now you are on the right track .

@Wayne: Thank you. There were different reasons. Minor problems like a not working rev limiter ( ign cut only works at 100% for us with a small RPM range ), sometimes it was a faulty boost pressure control with a peak of 3.3 bar boost pressure. The broken irons came from the boost peak. The fuel and ignition map was only tuned up to 2.5bar as we didnt wanted to go over 2.2 bar of boost in the beginning. There were just no rows filled in this high boost pressure area :-). Or it was just a mistake in the tune. At first we did not know how a rotary engine response to ignition advance/retard. In some cases we were way too aggressive. But since we have switched to a CO2 boost pressure control and running a conservative ignition there is nothing happening at all and the engine is running well.

@Julio: You are right. We learned it the hard way :-)

that thing must be really loud.

That is awesome, thanks for sharing

Epic, just epic. You've done the hard yards and should now get to enjoy the rewards of your development time... Till you do the next round of modifications :-).

@Raymond: After 10 years of racing a beetle with a stinger exhaust it does not shock me anymore :-). Soon there will be a Bridgeport, then it should be a bit louder :-)

@Zac: Luckily, there is not so much to change regarding the engine. Another Bridgeport and more boost and then we'll be fine :-). We're hoping to shoot in the 7 seconds on the 1/4 mile this year and then we achieved everything with this car. Rotary engines are addictive and we just do not know what to do then :-)

And thanks a lot Chris.

This thing is pretty cool. If it already has a semi peripheral intake it probably won't get much louder. What sort of power are you expecting to see your ET goal?

Since our chassis is pretty good, we think that we should reach the 7 seconds with 850 hp at the rear wheel. We had the car once on the Dyno in 2015, there were nearly 650 hp at the rear wheel and a 8.57 sec for the 1/4 mile pass. The automatic transmission makes it a bit more difficult, of course.

Sad weekend for us with the first passes on methanol after the rebuild. We are looking for reasons but we destroyed the engine as it reved up to 12k rpm although the rev limiter was set to 8k rpm. We think that we lost traction and the ECU could not stop the inertia of the engine.

Burn out


Another reason could be that something in the drivetrain is broken. We now have to disassemble the car and have a look at all the parts.

It is very annoying because the engine was running extremely well. Although it was the first tests on methanol. We were able to go to 2.4 bar boost pressure and had very good EGT and lambda values. Well it does not help. We now have to rebuild the engine and continue testing in Sweden in 4 weeks.

Condolences Marc, that's never a great situation.

Had a bit of a chat about it around the office this morning, and none of us could see how with your rev limit set at 8k, you'd see 12k rpm. If the ECU removes fuel or spark, it should stop the engine accelerating to higher RPM's almost instantly, as the force accelerating the engine has been removed. That being said though, rotaries revving through rev-limits is an uncannily common occurance :-(.

Have you got any Logs or data we could have a look through? Watching the video, it does sound like a driveline issue to me, slipping clutch? The revs seem to be pretty stable, then shoot up very suddenly. I take it you've not got much of a flywheel on there, so a pretty small rotating mass, possibly the engine accelerates too quickly on a free-rev for the ECU to catch it?

Small victories though, your burnout sounded amazing.

Rev limit should catch it pretty well if that calculation is syncronous, you should only get one or two power pulses before it cuts on an overspeed, if that fuction is at a longer system cycle time (100hz for some functions on some ecus) might bump up a fair way with no flywheel and half a dozen 3.5 bar absolute combustion events. Might be worth checking with ecu manufacturer how the rev limit is handled, syncronous with fuel and timing or at a nominal clock speed with other inputs.

I can't see 1 or 2 power pulses even with a broken flex plate bumping the engine speed up 4000rpm if rev limit is syncronous calculation, inertia would hold revs not keep rising.

May be potential for driveline shock weirdness with triggering if still using the dizzy post CAS rather than a true crank trigger. Might be worth going to an FFE trigger kit while it is apart.

@Zac: Thank you. I am in a facebook group that is made by the Fueltech guys. I told them about our situation and everybody is convinced that either we lost traction or something in the drivetrain is broken. We are running a 2-speed powerglide that is good for 1200 hp. To me it is the lost of traction just before the rev limiter and so the inertia of the motor couldnt be stopped by the ecu. There are some 6 seconds rotary guys in this group and they confirmed that thios could happen on a rotary engine. One guy had this problem with a rev limiter set to 10k rpm and his motor reved to 16k rpm when his clutch died.

As you can see in the datalog the ignition cut was at 100%. I have sent the datalog to Anderson Dick from Fueltech and he confirmed that everything worked as it should.

@Michael: Yes we are running the CAS but we never had a problem with it. We talked a lot with the fast rotary guys about a trigger system, especially your mentioned full function engineering system but almost everybody told us that if we consider the variance of the CAS at higher speeds, there is no problem with that. Our CAS deviates by approx. 2.5 ° from 2000 to 6000 rpm. We have taken that into account in the ignition map.

Our limiter is set to 100% ignition cut with a 100 rpm range. But it is a good point to ask them if they cut both the ignition and the fuel. I dont think that they cut both because i can choose in the setup if i want to cut fuel or ignition.

ps: We were able to drive from the track so i cant imagine that something in the drivetrain broke. It was a very poor track.

Attached Files

I wasn't refering to fuel and ignition cut but the frequency at which the rev limit logic is applied, is it calculated/applied with the engine sequence functions of ignition and fuel outputs or at a lower fixed loop speed like temperature sensor inputs etc? If people can clutch in limiter bash with rotaries on other ecus there must be a firmware issue letting this happen surely?

If the rev limit is working and it is just the last combustion event after driveline failure imparting enought energy for a 4000rpm engine speed increase in 180 crank degrees. I guess you could estimate the rotating inertia, charge mass and combustion efficiency and see if that energy tranafer matches or not.

Like Michael, after seeing that screenshot Im not convinced that the RPM limit is working properly either. When any limiter is applied I would expect to see the Lambda start to move in the lean direction fairly quickly at a high RPM.

You can see for instance when the two-step limiter applies more than 50% cut the lambda starts to go lean right away, yet when the RPM limiter is applying 100% cut the lambda isnt showing much/any reaction at all.

Or has it accidentally been tied to a logic input for gear selection/clutch input such that it is dissabled or looking at an incorrect input setting?

@Michael: Now i think i got you. It is sometimes difficult for us Germans to follow technical conversations in English :-) . I do not know how the exact routine of the rev limiter works. I only select if i want to cut Ignition or fuel and how much % i want to cut at what rpm range. For the rest i have to ask Fueltech. I attached some screenshots of the relevant settings. " Or has it accidentally been tied to a logic input for gear selection/clutch input such that it is dissabled or looking at an incorrect input setting? " That is a good point. We tested the so called " burn out mode " for the first time. It is activated by a dash button and sets 2 rev limiters. One for the 2-step and one for the burn out. Maybe something went wrong.

@Adam: You are completely right. I have not seen that yet. Maybe it actually has to do with the burn out mode we tested the first time. Maybe it was a chain of unfortunate circumstances. Traction loss and a non-functioning rev limiter. When doing the burn out before the run there was no problem as you can see in the screenshot.

Attached Files

You English is pretty good. I'm very dissapointed my mother didn't push me to learn Italian as a child, there are a lot of second generation Italian and greek migrants in Australia who only speak English

Ok, we have found what went wrong. It seems that only some revs before the rpm limiter our low gear band and the clutch of the first gear broke.

The engine itself, the rotors and all seals look as if they never ran. Only the front iron is broken.

Unfortunately i have a little dent on rotor one that is a sign of pre-ignition or detonation. But i will ask that in an extra thread. Currently we are overhaulin the transmission and the engine and will soon be back on the track :-)

I've seen this car on vwvortex, love it. and mk1 for life!

Ah ok, i missed it. Glad you like it :-)

And i have some good news about the car. We have rebuilt the transmission and the engine.

According to some advices from here and some other people we switched to the NGK 11.5 plugs and it works. We went to sweden last weekend to test it on the 1/8th mile. It went faster from run to run and the engine is still alive hahaha :-).

We have to tune it a lot more but i think we can manage it to do constant runs in the future. In 2 days we will go for some test runs on the 1/4 mile to see if and how the chassis works at higher speeds. I am not sure about the tune as the car made only 190 km/h on the 1/8 mile but we will see.

Here are some videos from our trip to sweden ( sorry for the bad quality :-( )

final run

final burnout

passing by

Burn Out Mode - software test

Marc I wish you guys good luck for the upcoming season. See you guys at the track!

Thank you Jesus. Looking forward meeting you this year !

We are ready for the racing season :-)

Super old thread, and sorry for the dig up for those subscribed to notifications, but just thought i would add my 2 cents as to why you saw your rev limiter never work.

You have mentioned that you now run R6725-115 plugs, which means you were not running these before. Rotaries run oil in their fuel, methanol rotaries run a LOT of oil in their fuel. In the right conditions, with the wrong plugs, the spark plug essentially turns into a glow plug and the amount of fuel and oil will ignite by itself with the wrong spark plug aka "dieseling".

How do i know? Ive seen it, and experienced it first hand, myself. I had the exact experience with my methanol auto 2 rotor setup (i have not come across many others that have experienced it, however, those that have seem to also have run an auto, so i wonder if the prolonged combustion heat over a greater period on the 2 step causes it?). On the 2 step, the limiter would not catch the engine at all, even though the 2 step was 100% active. I changed plugs from the denso 'like for like heat range' ones that were in it to some tried and true NGK R6725-115, and the next rip and every subsequent time, the limiter worked fine.

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