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Maximum RPMs on stock DJ 2.1 ?
Posted: Sun Feb 16, 2014 7:12 am
by riseabove
I know of the Digijet stock 5500 revlimiter and also how to bypass this .
My question is how much more could an engine take if in good condition ? 6250 / 6500 ?
i do know i dont gain power when revving it higher i just need the extre revs for som top-end speed
Im asking because im going to run this engine in a 1303 superbeetle with 225/50-17 rear wheels
and full-racing-transaxle with finnishmade close ratio racinggears and a bmw e30 lsd that has been custommade for me.... as im a beginner when it comes to
transaxles i got my gearing a "bit" off and ended up with needing more revs than 5500 to get at least 140km/h out of my car.
Im not about to start ripping apart my transaxle anytime soon to change out the final drive or so .
Longlivety is probably not the main concern
Re: Maximum RPMs on stock DJ 2.1 ?
Posted: Mon Feb 17, 2014 9:09 am
by AMBROSIA
I would at least be fitting bolt up rockers and replacing the hydro lifters with solid T4 ones.
Stock rods would also be a concern above 6k.
Re: Maximum RPMs on stock DJ 2.1 ?
Posted: Mon Feb 17, 2014 10:18 am
by riseabove
That was about the same conclusion I came to. New lifters and rockers it is then
Stock rods can handle this i am sure. If not it will be a beautiful bang sooner than later....
Re: Maximum RPMs on stock DJ 2.1 ?
Posted: Tue Feb 18, 2014 9:18 am
by buildabiggerboxer
You get a better and lighter lifter by converting the original German hydros to solid, just gut them and have a tubular spacer machined up to fit under the push rod cup at the correct height, you just want the circlip to go in snug, the Febi solid T4 lifter fits o.k, but it's heavy and will need new longer p/rods, I've run this setup with stock steel 2.1 pushrods at 7000 rpm..
the trick with the con rods is to use a stretch gauge and torque the 2.1 bolts for no ore than .005" stretch, usually this is between 29 and 32 lb/ft, if they stretch to over .010" at 32lb/ft use new bolts, as they are weak and beyond use at this amount of stretch and about to break, the 2.1 bolts are available new
still, just use the above method to weed out bad ones, it's not the rod but the bolts the fail, VW cocked up with the extra 1/2 turn specified after the torque value, if you don't have a stretch gauge, you can use a micrometer if you are careful, as the end of the bolt is not flat so can give false readings.
Re: Maximum RPMs on stock DJ 2.1 ?
Posted: Tue Feb 18, 2014 9:50 am
by Piledriver
You may be ahead dropping a set of H beams in it (if you had it apart)
The stock rod big ends go highly egg shaped simply with high mileage on a 2.1.
This eventually results in poor oil pressure>spun bearing>ventilated block.
Re: Maximum RPMs on stock DJ 2.1 ?
Posted: Tue Feb 18, 2014 3:31 pm
by AMBROSIA
I ditched the stretch 2.1 bolts for a set of low mileage non stretch from a 1.9.
Out of interest has anyone tried the higher rev hydro lifters that i've seen available?
Re: Maximum RPMs on stock DJ 2.1 ?
Posted: Wed Feb 19, 2014 3:34 am
by riseabove
Ah thank you for this information . i will surely look into modding my lifters .
At this time i do not want to split my case as i know the costs will start to rise as it always does when you open an engine up. "i might aswell...."
The plan is to ditch the wbx alltogether when i have the funds for it and get myself a 13b wankel instead .
The reason for wanting more revs is this little fellow
Gearing is as follow :
Finalgear 4,125
First 3,4
Second 2,13
Third 1,7
Fourth 1,26
all uprated quality gears....
and to top it of my transaxle-friend made me a one off special with a lsd diff out of a BMW m3......
Re: Maximum RPMs on stock DJ 2.1 ?
Posted: Wed Feb 19, 2014 9:34 am
by buildabiggerboxer
riseabove wrote:Ah thank you for this information . i will surely look into modding my lifters .
At this time i do not want to split my case as i know the costs will start to rise as it always does when you open an engine up. "i might aswell...."
The plan is to ditch the wbx alltogether when i have the funds for it and get myself a 13b wankel instead .
The reason for wanting more revs is this little fellow
Gearing is as follow :
Finalgear 4,125
First 3,4
Second 2,13
Third 1,7
Fourth 1,26
all uprated quality gears....
and to top it of my transaxle-friend made me a one off special with a lsd diff out of a BMW m3......
No need to split the case, the followers can be pulled as it is, I use a magnet or small slide hammer for sticky ones, refit with quality sprung P/rod tubes, Wassers thermal control is very good, so they don't expand as much as air cooled motors and run quiet enough even on solid lifters.
Re: Maximum RPMs on stock DJ 2.1 ?
Posted: Wed Feb 19, 2014 1:53 pm
by riseabove
buildabiggerboxer wrote:
No need to split the case, the followers can be pulled as it is, I use a magnet or small slide hammer for sticky ones, refit with quality sprung P/rod tubes, Wassers thermal control is very good, so they don't expand as much as air cooled motors and run quiet enough even on solid lifters.
This much i know

Any good tips for material for making the "stop-pieces" for the lifters ? i have gotten the tips to use JM7
Alu/bronze .
Sprung p/rod tubes are in the plan to get anyways so that was a good idea .