Red Rose - CR & Chamber Volumes
Discussion
Thought people may be interested in some info re 4.5 Red Rose heads.
I have my engine in bits (head gasket primary cause) and decided to blueprint the bottom-end at same time, complete with fine balancing – TVR Power doing that. I’m working on the heads – measuring things up as well as refurbing.
According to Jason at TVR Power the CR of a Red Rose is 11:1 – which is higher than the original 4.5 model which was 10.75:1 before the CR was reduced by the factory to make it run smoother and on 95 RON.
Anyway here are the chamber volumes I measured and individual cylinder CRs calculated on standard head gasket:
Cyl Ch Vol CR
1 48.1 10.67
2 45.3 11.16
3 48.0 10.68
4 46.1 11.01
5 46.9 10.87
6 47.8 10.72
7 47.0 10.86
8 48.2 10.65
This gives an average CR of 10.83:1. But look at the range – 2.9cc!
Interestingly there is a commonality between pairs of cylinders on the odd bank with 1-3 very close and 5-7 very close – unfortunately there’s a 1cc difference between them. The even bank just seems to vary front to back.
The RR chambers have been opened out by hand and show minor variations as consequence (done to a price need it be said), however I suspect there is variation in the underlying castings to get that much difference. I’m having a hell of a long job getting them balanced – this heat doesn’t help either. COLD BEER
!!
I have my engine in bits (head gasket primary cause) and decided to blueprint the bottom-end at same time, complete with fine balancing – TVR Power doing that. I’m working on the heads – measuring things up as well as refurbing.
According to Jason at TVR Power the CR of a Red Rose is 11:1 – which is higher than the original 4.5 model which was 10.75:1 before the CR was reduced by the factory to make it run smoother and on 95 RON.
Anyway here are the chamber volumes I measured and individual cylinder CRs calculated on standard head gasket:
Cyl Ch Vol CR
1 48.1 10.67
2 45.3 11.16
3 48.0 10.68
4 46.1 11.01
5 46.9 10.87
6 47.8 10.72
7 47.0 10.86
8 48.2 10.65
This gives an average CR of 10.83:1. But look at the range – 2.9cc!
Interestingly there is a commonality between pairs of cylinders on the odd bank with 1-3 very close and 5-7 very close – unfortunately there’s a 1cc difference between them. The even bank just seems to vary front to back.
The RR chambers have been opened out by hand and show minor variations as consequence (done to a price need it be said), however I suspect there is variation in the underlying castings to get that much difference. I’m having a hell of a long job getting them balanced – this heat doesn’t help either. COLD BEER
!!Would suggest to me your even bank head is not flat in such a sense.
1 48.1 10.67 2 45.3 11.16
3 48.0 10.68 4 46.1 11.01
5 46.9 10.87 6 47.8 10.72
7 47.0 10.86 8 48.2 10.65
Progressively reducing numbers front to rear. That much variation is not good. Do you have any detonation dange on Pistons 2 and 4 at all?
1 48.1 10.67 2 45.3 11.16
3 48.0 10.68 4 46.1 11.01
5 46.9 10.87 6 47.8 10.72
7 47.0 10.86 8 48.2 10.65
Progressively reducing numbers front to rear. That much variation is not good. Do you have any detonation dange on Pistons 2 and 4 at all?
Pleased my post is proving interesting - hope I haven't missed anyone in the following reply.
I got the diff about 18months ago from Dana Spicer having been put in touch with them by the factory. It’s solid mounted so no chance of it moving about although get interesting, quiet spooling up whine from it in the cabin. Made a huge difference to the way the car feels on the road. Always on the boil, vivid response, although cruising not as relaxed - but overall great.
Long story re head gasket, but basically it was caused by overheating. This mainly as result of having a custom exhaust manifold made that wraps around front of engine in order to get the tuned length right. It’s fully lagged so under-bonnet temp has not changed, but all that big bore pipework has blocked escape route down side of engine for hot rad air, and generally reduced under-bonnet space. The impact of this wasn’t realised during prolonged time on rolling road getting remapped for the exhaust nor on the drive home (Norfolk-Edinburgh) even when air in the coolant system stopped the journey 50 miles from home. It took quite a time and many futile fixes before it became clear the basic prob was there was no rad airflow below about 55 mph, hence instant overheating in traffic…. Doh! Whole other story here on the cooling system sub-project……….
Basically yes – Vaseline, with burette and white spirit, with head levelled off on bench and Perspex clamped down to prevent leakage.
Ridds – pleased to say no detonation damage on 2 and 4. I wouldn’t have expected it as the engine is supposed to be running at 11:1 and the ignition mapping has been sorted for this compression – initially by the factory with its MBE chip and later by Dave Walker with the Emerald ECU. Although having said that I was surprised by the number of sharp edges in the chambers – edge of spark plug threading; seat insert maching; rough casting marks in corners. These will be smoothed off during balancing.
Good point about the head deck may not be at the same height front to back. I don’t know how to check this as there is no obvious machining datum line for the head. Been skimmed now unfortunately. However is definitely a lot more variation in chamber size from the factory deshrouding work that was done on this bank compared with other. I guess combination of the two would account for the differences.
Agree not good that’s why I’m currently balancing the chambers to a target 47 cc. The odd bank are all at that now – and I’ll be starting on the even bank this morning. The engine will be running a thinner copper head gasket so that will give a nice smooth 11.2:1 CR. I’ve talked this through with TVR Power and another AJP8 expert and view is that as long as everything is set-up correctly – including less ignition advance of course – the motor can handle this sort of compression.
Cheers
simonsparrow said:
Interesting profile, I've read about your car in sprint a while ago. Did you get that diff ratio from the factory, or was the diff changed afterwards? What caused your head gasket problems?
I got the diff about 18months ago from Dana Spicer having been put in touch with them by the factory. It’s solid mounted so no chance of it moving about although get interesting, quiet spooling up whine from it in the cabin. Made a huge difference to the way the car feels on the road. Always on the boil, vivid response, although cruising not as relaxed - but overall great.
Long story re head gasket, but basically it was caused by overheating. This mainly as result of having a custom exhaust manifold made that wraps around front of engine in order to get the tuned length right. It’s fully lagged so under-bonnet temp has not changed, but all that big bore pipework has blocked escape route down side of engine for hot rad air, and generally reduced under-bonnet space. The impact of this wasn’t realised during prolonged time on rolling road getting remapped for the exhaust nor on the drive home (Norfolk-Edinburgh) even when air in the coolant system stopped the journey 50 miles from home. It took quite a time and many futile fixes before it became clear the basic prob was there was no rad airflow below about 55 mph, hence instant overheating in traffic…. Doh! Whole other story here on the cooling system sub-project……….
rev-erend said:
How are you measuring the volume ? Piece of glass with drilled hole with grease smeared around egde of chamber !
Basically yes – Vaseline, with burette and white spirit, with head levelled off on bench and Perspex clamped down to prevent leakage.
ridds said:
Would suggest to me your even bank head is not flat in such a sense.
1 48.1 10.67 2 45.3 11.16
3 48.0 10.68 4 46.1 11.01
5 46.9 10.87 6 47.8 10.72
7 47.0 10.86 8 48.2 10.65
Progressively reducing numbers front to rear. That much variation is not good. Do you have any detonation dange on Pistons 2 and 4 at all?
1 48.1 10.67 2 45.3 11.16
3 48.0 10.68 4 46.1 11.01
5 46.9 10.87 6 47.8 10.72
7 47.0 10.86 8 48.2 10.65
Progressively reducing numbers front to rear. That much variation is not good. Do you have any detonation dange on Pistons 2 and 4 at all?
Ridds – pleased to say no detonation damage on 2 and 4. I wouldn’t have expected it as the engine is supposed to be running at 11:1 and the ignition mapping has been sorted for this compression – initially by the factory with its MBE chip and later by Dave Walker with the Emerald ECU. Although having said that I was surprised by the number of sharp edges in the chambers – edge of spark plug threading; seat insert maching; rough casting marks in corners. These will be smoothed off during balancing.
Good point about the head deck may not be at the same height front to back. I don’t know how to check this as there is no obvious machining datum line for the head. Been skimmed now unfortunately. However is definitely a lot more variation in chamber size from the factory deshrouding work that was done on this bank compared with other. I guess combination of the two would account for the differences.
Agree not good that’s why I’m currently balancing the chambers to a target 47 cc. The odd bank are all at that now – and I’ll be starting on the even bank this morning. The engine will be running a thinner copper head gasket so that will give a nice smooth 11.2:1 CR. I’ve talked this through with TVR Power and another AJP8 expert and view is that as long as everything is set-up correctly – including less ignition advance of course – the motor can handle this sort of compression.
Cheers
Very interesting, hope you get on well! I've noticed on my standard 4.2 that cooling is marginal in this weather, even with a fan override switch. I'd like to get a bonnent and modify it with a vent to allow the air from the radiator out, perhaps like the Lotus Elise has.
Diff change sounds interesting, so you've replaced the BTR (I think thats what is standard) with a Dana? Was there a lot of fiddling with drive shafts and propshafts required?
Oh, and the exhaust sounds interesting too, I've often thought forward facing could be the way to go, I know of a Cerbera racer that uses a Tuscan style side-exit system, but this needs to go through the passenger footwell.
Diff change sounds interesting, so you've replaced the BTR (I think thats what is standard) with a Dana? Was there a lot of fiddling with drive shafts and propshafts required?
Oh, and the exhaust sounds interesting too, I've often thought forward facing could be the way to go, I know of a Cerbera racer that uses a Tuscan style side-exit system, but this needs to go through the passenger footwell.
Edited by simonsparrow on Thursday 27th July 09:16
simonsparrow said:
.....Diff change sounds interesting, so you've replaced the BTR (I think thats what is standard) with a Dana? Was there a lot of fiddling with drive shafts and propshafts required?
Edited by simonsparrow on Thursday 27th July 09:16
Dana are the people in UK who supply the std diffs - so it was a straight swap.
dean_ratpac said:
do you have any photos of the set-up at all? very interesting thread BTW.cheers. Dean
Thanks Dean – yes have pix and intention is to put them on web but still waiting on blueyonder for my own space (and time). Here’s a couple, one of exhaust...
http://s40.photobucket.com/albums/e23
http://s40.photobucket.com/albums/e23
If anyone has anything specific they'd like to see re engine strip let me know and if I've got any I'll try and put them up.
Cheers
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