Compression ratio for modified Mi16

I'm finally finishing the car off tomorrow morning, will take a look before refitting the aircleaner. It would be good to check the compression, if up around 200 or above it would have been modified I would say.
 
Use this DCR calculator. It's very good.

Dynamic CR


With 11:1 static and the 280 cam, I get 8.7:1.
 
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So, after reading up on DCR, this looks to be OK.
 
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Cam looked stock, 380 thou lift, maybe the compression has been increased? I'm thinking a set of flat top pistons in one of these could be a go, would be around 9.5 to 1.
Car ready to go, are you going to help Kosta come and get it?


GRAHAM WALLIS said:
I'm finally finishing the car off tomorrow morning, will take a look before refitting the aircleaner. It would be good to check the compression, if up around 200 or above it would have been modified I would say.
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I'm confused Graham. What are you talking about?
 
Sorry Peter, answered you and Craig in separate posts. My reply to you suggested that 8.7 to 1 DCR may be OK for the 16V. Answer to Craig was about his 75 kw engine. I have finally found the complete specs for the Piper Ultimate Road cam with solid lifters.
 
GRAHAM WALLIS said:
Cam looked stock, 380 thou lift, maybe the compression has been increased? I'm thinking a set of flat top pistons in one of these could be a go, would be around 9.5 to 1.
Car ready to go, are you going to help Kosta come and get it?
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Interesting.... I’ll send you a PM
cheers
Craig
 
Project abandoned, in the end I couldn't see how it would improve things, slightly more compression and bigger cams wasn't going to give me what I wanted (just more power up top where I have too much already) so will simply fit a GTi6 manifold in place of the 45 mm Jenveys. Will fit the Piper adjustable pulleys at least and have a play on the dyno. This ought to give some more mid range and with the 4.8 final drive to be fitted it will be as good as I can get it for what I want. A few dollars wasted I guess! Add to the growing list of modifications that I have removed from this car.
 
Yep, I know what you mean. I got off on the wrong foot with all of this and one thing lead to another. Final straw was when the rod fitting was done poorly. I will probably keep the engine project for a while, I'd never get back what I spent, may be suitable for Rallycross use. Got the GTi6 manifold fitted and working today ( very impressed by the inlet trumpets on the runners) and there is a time slot available at the tuners on Thursday, hopefully I'll have some interesting results by Friday.
 
Keen to see the dyno sheet with that inlet on the XU9.
 
Me too, going down same route and I appreciate your sharing of learnings
 
Almost wasn't going to happen tomorrow, no way could I communicate with the ECU from my Lap Top. The tuner was busy all day but in the end dropped over to confirm that his Lap Top did, phew! Will reload Tuner Studio from the MS website tonight. Fitted the adjustable pulleys as well so should be an interesting session. Running very rich as I couldn't access the ECU but at the times it wasn't misfiring it seemed to have plenty of go. The space around the throttle body is very much sought after by a host of different things, may have to do some rearranging.
 
I will put up the sheet with Jenveys as well as the one from tomorrow.
 
Do a proper comparison of throttle bodies and inlet manifold before the cam timing changes.
 
Yes, planning to do that, looks like a lot of people showing interest in this.
 
My prediction is the inlet manifold change will do very little but the cam timing will do what you want and move the power band around.
 
Even if the torque isn't increased and I think it will be with the longer smaller diameter runners and plastic resonator, the engine will sound a lot nicer when under load in the midrange.
 
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