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Xe Cams In Let

517 views 7 replies 5 participants last post by  AJRAT 
#1 ·
Have just been reading the thread on an xe inlet cam and have this problem: I recently put a coscast head on my let but, like a fool, left the xe cams in. I then exchanged the head so they are gone. I don't know why i didnt swap them! The car is fine untill max torque ish - about 3000 rpm. It then acts as if the clutch is slipping and i wondered if the overlap was blowing the gas through to exhaust? Shall i buy another let exhaust cam? Shall i buy some vernier stuff? Cheers
 
#3 ·
It has just had an engine rebuild and f28 so has been off the road for 3 months but is insured again and on the road tonight! It is aubergine with 5 stud hubs ( turbo wheels) and no badges.

Do you frequent Rainham often? If so see you around!
 
#4 ·
AJRAT said:
...i wondered if the overlap was blowing the gas through to exhaust? Shall i buy another let exhaust cam? Shall i buy some vernier stuff? Cheers
vernier stuff is good if you are prepared to experiment a little and optimise
I think you need the LET exhaust cam in any case

If you run stock KKK turbo and intake, you won't be blowing boost through the exhaust, rather the *opposite* will be happening (contaminating and pre-heating the intake!)

I know this is not the accepted theory, but sitting here under the tropical sun I've done some calculations on the subject. If you need the long version post a question and we take it from there.:beer:
 
#5 ·
If you run stock KKK turbo and intake, you won't be blowing boost through the exhaust, rather the *opposite* will be happening (contaminating and pre-heating the intake!)
could this happen when running low boost and Xe inlet and Let exhaust cam. (This is basically what I am doing at the moment.

thanks muppet.
 
#6 ·
It depends on the backpressure created by the turbine housing and the rest of the exhaust.
If they're all stock, then there's always gonna be more pressure in the exhaust side of the head ports -and guess what? during overlap the crap is stuffed back into the cylinders, contaminating and preheating the fresh charge. More overlap (in this situation) can only get things worse)
That's why you need the vernier wheels to retard the inlet and bring overlap back on spec

Don't mention this to so-called UK 'tuners' , they won't know that you're talking about lmao
 
#7 ·
> Do you frequent Rainham often? If so see you around!

hay thats place sounds familair...wait I live there!
Don't see may Astras about, but I manily drive up and down the lower Rainham road rather than the A2 area etc.

Well to get your C20LET running right, I would fit the C20LET cams back in, but, as mentuoed, does require to run it all back in and new boltsmgaskets etc...

I'm rebuilding my C20LET (calibra) and sticking to the std C20LET cams.
 
#8 ·
yes the standard cams are much better than the stupid xe jobs! new turbo cams are £200 each from vauxhall! Best start saving.
I have seen a couple of calibras along the lower road. What colour? Just built my let too. Bit of head work, Arp bolts, 6 speed fitted sillicon hoses everywhere-bloody fortune!
 
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