Discussion
There were literally no miles on the car. Only cam bedding then we loaded it up on Dales rollers to bed the rings in. This worked as it was fairly smokey at first with the thin break in oil. Was much better later with vr1.
I was suspicious of those terminal speeds but hear the GTR guys had matching numbers on their fancy data loggers.
I had the same jets on the nitrous systems as I had previously and I knew the AFR used to go off scale rich when it was 3.5 bar fuel pressure. I am now back to 2.5 bar so was careful to watch the gauge. It hovered around 11:1 which I thought was perfect but am now thinking that average on all cylinders may have left 1 or 2 to lean out. We will find out come Friday when I pull the head.
I was suspicious of those terminal speeds but hear the GTR guys had matching numbers on their fancy data loggers.
I had the same jets on the nitrous systems as I had previously and I knew the AFR used to go off scale rich when it was 3.5 bar fuel pressure. I am now back to 2.5 bar so was careful to watch the gauge. It hovered around 11:1 which I thought was perfect but am now thinking that average on all cylinders may have left 1 or 2 to lean out. We will find out come Friday when I pull the head.
Looking forward to getting home tonight and start the strip down. It's been on my mind all week and I fear some serious damage.
Also after repairs I am fitting a vernier timing set and setting the cam with 4 degrees retard. Then the nitrous system is getting a makeover and will be operated using the MS2.
Also after repairs I am fitting a vernier timing set and setting the cam with 4 degrees retard. Then the nitrous system is getting a makeover and will be operated using the MS2.
Sardonicus said:
Nitrous piston failure pure and simple 
Derek you know already this is a distribution problem right there 
real shame knowing what you put into this already 
and before anyone pipes up this as got nothing to do with break in 
Race engines get broke in at the track Derek you know already this is a distribution problem right there real shame knowing what you put into this already and before anyone pipes up this as got nothing to do with break in 
Yes my bad i am afraid. I knew it would be leaner but thought 11:1 on the gauge would be fine. Another costly lesson.
Ive spoken to Roland and will be dropping the block etc off next Friday.
I also see witness marks on one piston from the inlet valve. I also knew i was running close on the inlets after timing the cam and the best i could get with the timing gear i had was a few degrees advanced. So new timing gear will be used and the cam will be retarded. May even see some more peak bhp.
Pupp said:
When you built the engine, and assuming the same heads were re-used from the previous motor, did you make any allowance for the hike in CR resulting from the increase in swept volume caused by the bigger bores? Could well have tipped it over the det threshold if it was close, all else being equal
I asked Roland at ACR and he said all things being equal his 96mm forged pistons with standard 40 thou gaskets and 28cc heads would normally come to around 10.4:1I used 50 thou MLS gaskets and my heads are about 29cc. The block has been decked a little and I don't have the deck height figures with me at the moment. I will be checking it all again when I get the block reassembled before ordering new MLS gaskets. I want to aim for low 10's if I can.
Alexdaredevils said:
I won't even mention LS
Oh wait........
Let's see what car is top of the 1/4 mile table. Oh yes it's mine with a little 4.6 rover engine. Maybe in a couple years Alex when I am trying to get top spot back off Neal.Oh wait........
Latest theory is that the ring gaps were too tight. This will be addressed.
fatboychim said:
Hi Anthony,
Had loads going on this year so the chims been mostly collecting dust, I still have your Y piece and am jealous of your track day, I love Combe. Must get back on track before summer is out, anyhoo don't want to tread all over Derek's thread so I'll slip back into lurk mode.
Don't worry about that I do it all the time. Had loads going on this year so the chims been mostly collecting dust, I still have your Y piece and am jealous of your track day, I love Combe. Must get back on track before summer is out, anyhoo don't want to tread all over Derek's thread so I'll slip back into lurk mode.
Pants.
I dropped the block etc off at ACR on Monday. I managed to get there and back from Salford in a 90 minute extended lunch.
I phoned yesterday to be told it hadnt been touched yet and probably wont be ready next week. I know that Roland is in Malaysia till 17th. Guess things dont move on as fast when hes not there. Oh well guess i have time to sort the garages out. Finally get rid of the Jensen shell, relocate the SD1 and make a start on that. Its not been a great year for me missing a lot of racing, cruises, car shows and meets. I hope this year is for development and next year will be fun packed with lots of successful racing.
I dropped the block etc off at ACR on Monday. I managed to get there and back from Salford in a 90 minute extended lunch.
I phoned yesterday to be told it hadnt been touched yet and probably wont be ready next week. I know that Roland is in Malaysia till 17th. Guess things dont move on as fast when hes not there. Oh well guess i have time to sort the garages out. Finally get rid of the Jensen shell, relocate the SD1 and make a start on that. Its not been a great year for me missing a lot of racing, cruises, car shows and meets. I hope this year is for development and next year will be fun packed with lots of successful racing.
In some dark moments last night i considered turbo option.
Lower the CR with a little head work and thick MLS gaskets
I think ive proved a point that nitrous can provide amazing power and torque and you can kind of have your cake and eat it. But as i use the car less on the road and trailer to race meetings maybe a 500 bhp turbo is the way forward. I can still add nitrous to take it to 600 and run in the 9's i reckon.
Lower the CR with a little head work and thick MLS gaskets
I think ive proved a point that nitrous can provide amazing power and torque and you can kind of have your cake and eat it. But as i use the car less on the road and trailer to race meetings maybe a 500 bhp turbo is the way forward. I can still add nitrous to take it to 600 and run in the 9's i reckon.
Sardonicus said:
hy what's wrong with your block Derek ? Though you just needed a couple of T H liners doing
To fix it properly ACR want to fit all 4 liners on the offside. Also the decks would be machined again. He also talked of multiple heat cycles and I thought maybe there's not much life left in this old dog so for the difference I have opted for one of their remanufactured blocks. No fear of dropped liners, new core plugs etc. I thought the price very fair.
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