What option to choose to get the engine running
Turbo Mini Forums

Hey Guys,

I am still not further with my engine setup. So to where i am if not known from my other threads:

I bought an turbo engine with a dizzy and a CR of 9:1 and want to run it at 10psi. The engine was built and set up by someone who knew his job and also drove it for a longer time with a T3 turbo. The guy i bought it from fitted a new turbo to get more power at lower rpm. It was basicly a hybrid of a T2 and a T3. He never ran it and i didnt know enought of the topic to know that this might now work.
Anyway, after 1 and a half year and several thousand euros on repair and rebuilds i still have the engine misfireing / leaning off at the transit to boost.
My guess is that the ignition curve of the dizzy just doesnt fit the turbo that delivers boost way earlyer now.

After thinking about fitting a 7 port turbo, i was thinking about a 7 port N/A engine and now im kinda back to getting the current setup to run. For that i need a new turbo for sure (the current one was burned by too late ignition). BUT i am afraid to invest money again and then fail at setting it up. Maybe the misfireing and leaning off is not from the ignition? I am afraid to fit a megajolt and have the same problem again.

So here are my option:

1. Fit a megajolt and keep the carb. Would be cheap and not much work to do. Would be somewhat easy to set up and could be set up at a RR. But maybe not solve the misfireing/leaning off issue.

2. Fit the SC 5 port Management kit with mapped ignition and FI. Since it takes care of fueling and ignition it would surely solve the issue but it seems to be a pretty hard way to set up. As far i was reading here at the forum the software is pretty complicated and noone has real experience with it. So i am not sure if i can get it running and if a RR operator could work with it.

3. Get a complete 7 port N/A engine with the same power as the turbo engine and let SC set it up This would work for sure but the price is rediculous high.

One problem is that here in austria there are not much RR operators who have experience with these engines. Also i would like to go with the Mini Spares Evolution helical gear kit and some good helical drop gears. Mostly because i guess i already lost some of my hearing from the S/C Drops and S/C gearbox

What would you guys do? I am willing to invest money and read into stuff, but i am afraid to invest money and then cant set it up again.

I’d stick with the 5 port turbo setup.

Have you got the part throttle lean off pipe attached? This can cause the symptoms you have.

In the 13's at last!.. Just

The part throttle lean off is blocked. I tried to open it, it didnt change the symptoms. neither does carb spring, damper oil, needle whatsoever.
The engine runs great off boost and great on boost - just the transit at low rpm doesnt work.
transit on high rpm ( over 4000) works also.

The only thing that changes the symptoms is the ignition. Retarding the dizzy makes it worse, advancing makes it better - but i dont want to go to more than 25° max advance on boost.


Edit:
Also would you keep the carb or use the SC EFI kit?

Edited by JackZwiebel on 21st May, 2019.

Thats a great looking engine bay

Did you get a base map for fueling and ignition from SC? On their homepage i only find maps for N/A engines.

Ok thanks. I will talk to some tuners if they think they can set up such an engine.

Just being curious, are you running a water cooled intercooler, or what is that can where the air hose comes from?

Have you tried the T-Piece trick?

Basically feeding the float bowl via a pipe from the plenum rather than internally.

Following on from that, is the restrictor ring still fitted in the plenum?

Personally, I'd fit a mappable ignition system and a wideband AFR gauge. Then you can drive around and set it up as you drive. There is a very good thread on here about polishing carb needles.

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Yes i tried the t-piece trick since i thought there might be a port blocked or something, but it didnt change a thing. The fueling is spot on off and on boost. Just on transit to boost on low rmp it leans off suddenly and backfires.
For example when i drive steady at 3000rpm and the road goes up a hill. So i dont accelerate, there is just more power needed, the turbo starts to set in and it backfires.

I do have a wideband AFR fitted and as sayed the fueling is spot on while on boost and off boost. If im on boost i can floor it and the engine responses perfectly fine. Just on the transit to boost the afr reads extremly lean (16-17) and it backfires.

What carb spring and oil are you using ?

Phil.

WWW.TURBO-MINI.COM

Thanks for the Info Steve, interesting setup!

Hallo Phil, I am running a green spring at the moment.
For oil i used the SU oil, 20w50 and transmission oil.
The transmission oil made it a bit better.

The ignition has a bigger effect. if i retard the ignition just a bit it gets way worse.

Has your carb got this link pipe?

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HOSS

Yes as sayed above i had the part throttle lean off connected but i blocked it. it made the fueling a bit more consistent in the other areas but didnt change anything on the problem

The turbo dizzy curve is compromise in every respect for even a standard engine.

I'd fit megajolt, or similar, as it may well fix your problem if you think it is related to advance on boost transition. If it doesn't, and you decide to go down a completely different route, there is always a market for working megajolt kits, so the monetary cost to try it out should be quite low.

Why not try screwing your bob weight plates together, and locking up at 25 or 27 degrees advance. It won’t be optimal, but it’ll work perfectly well, and isolate the dizzy variable.

Hey Dave, thats a pretty good idea, unfortunlx i already ripped the car apart since the turbo is leaking oil.(big blue smoke cloud on overrun). Thats why i want to change to a gt17. maxbe i try the fixed ignition with the new turbo first

While building up the car itself i try to wrap my head around ignition maps - i have been reading a bit on here and i am looking for a safe map to fire it up and drive a few miles befor going to the rolling road. I found a rolling road operaor who sayed he wil lset it up if its running and can get there by its own .
I have a CR 9:10 and plan to run max. 10psi boost with intercooler. I came up with this map:


what do you guys think of that map? I guess it should be a save starting point. Any suggestions?

I should try some new plugs

i did change the plugs once while trying to set it up, it didnt change anything. But i will for sure get a new set of plugs in befor starting after the rebuild :)

Any comments on the base map? Is it good and most important save for first test drives and the way to the rolling road?

any hint on what the map numbers relate to on the left hand side? i asume 1040 is roughly atmospheric ( at sea level) and 1840 about 10 psi boost. in which case yea it looks reasonable, but do check the tming matches a timing light.

yeah you are right it is in mbar - 1000mbar, being 1bar as atmospheric.

I will check the timing with a timing light, thanks

ah, mbar of course!

Somewhere on here is a map which replicates the turbo dizzy curve, which would be uber safe.