Duratec / imperial chassis build thread.
Discussion
Purespeed said:
Well I have to say I am a bit disappointed 
The first thing the Steve’s did was to check the compression ratio to see if it suited the plugs. It was found to be 190 psi give or take 5 on all cylinders and at that point the figure of 240 bhp was mentioned... I think mine is a compression ratio on 10.8 ish and Caterhams R500 is 12 ish. All very strange because the head was done by the same guy who does the R500 heads and as far as I aware there is only one set of Arrow rods and Omega pistons available for this engine. All I can think of is that the head guy also skims the caterham heads or more likely there in fact other pistons available and if thats true then I'm going to be far from chuffed with the suppliers as they knew what I was trying to get. I'll find out.
The advice I took when putting the engine together said that there was no need to key the crank/sprocket/pulley and because of this the revs were kept to a very conservative 8500rpm. At 8500 the power was still rising so there is certainly more power to be had if I get it keyed. Anyway other than the enormously disappointing 245 bhp and 166.2 lbft of torque the engine is a sweet as a nut. Steve G stood a £1 coin on the engine and it just sat there, it really is very very smooth. It's really drivable and still goes like a rocket.
So what have I learnt?
1,Should have discussed compression ratio with parts suppliers
2,I think using the C400 airbox along with smaller filter has restricted airflow
3,The 45 Jenveys should have been 48's and even better SBD's tapered T'B's.
4, key the crank/sprocket/pulley
The IVA is two weeks today…
Jason
Did the guy who did the head buret the chambers to check the CC? did he measure the chamber depth, Are you sure that the deck height of the block is the same and you have the same head gasket as the R500? Does the R500 caterham use pocketed pistons? all little tricks to increase the compression just that bit more although you're obviously no novice at this so I guess you've been around this. The first thing the Steve’s did was to check the compression ratio to see if it suited the plugs. It was found to be 190 psi give or take 5 on all cylinders and at that point the figure of 240 bhp was mentioned... I think mine is a compression ratio on 10.8 ish and Caterhams R500 is 12 ish. All very strange because the head was done by the same guy who does the R500 heads and as far as I aware there is only one set of Arrow rods and Omega pistons available for this engine. All I can think of is that the head guy also skims the caterham heads or more likely there in fact other pistons available and if thats true then I'm going to be far from chuffed with the suppliers as they knew what I was trying to get. I'll find out.The advice I took when putting the engine together said that there was no need to key the crank/sprocket/pulley and because of this the revs were kept to a very conservative 8500rpm. At 8500 the power was still rising so there is certainly more power to be had if I get it keyed. Anyway other than the enormously disappointing 245 bhp and 166.2 lbft of torque the engine is a sweet as a nut. Steve G stood a £1 coin on the engine and it just sat there, it really is very very smooth. It's really drivable and still goes like a rocket.
So what have I learnt?
1,Should have discussed compression ratio with parts suppliers
2,I think using the C400 airbox along with smaller filter has restricted airflow
3,The 45 Jenveys should have been 48's and even better SBD's tapered T'B's.
4, key the crank/sprocket/pulley
The IVA is two weeks today…
Jason
Edited by pikeyboy on Tuesday 8th February 08:07
pikeyboy said:
Did the guy who did the head buret the chambers to check the CC? did he measure the chamber depth, Are you sure that the deck height of the block is the same and you have the same head gasket as the R500? Does the R500 caterham use pocketed pistons? all little tricks to increase the compression just that bit more although you're obviously no novice at this so I guess you've been around this.
I have had little to do with Duratec at the moment. But I spoke tp Raceline who built my Zetec. I was speaking to Peter ref Caterham claiming 220bhp upgrade for R300 and 400. Edited by pikeyboy on Tuesday 8th February 08:07
I got the impression that anything over 210/215 bhp requires the pistons to be pocketed.
Purespeed said:
Well I have to say I am a bit disappointed The first thing the Steve’s did was to check the compression ratio to see if it suited the plugs. It was found to be 190 psi give or take 5 on all cylinders and at that point the figure of 240 bhp was mentioned... I think mine is a compression ratio on 10.8 ish and Caterhams R500 is 12 ish. All very strange because the head was done by the same guy who does the R500 heads and as far as I aware there is only one set of Arrow rods and Omega pistons available for this engine. All I can think of is that the head guy also skims the caterham heads or more likely there is in fact other pistons available that change the compression ratio and if thats true then I'm going to be far from chuffed with the suppliers as they knew what I was trying to get. I'll find out.
The advice I took when putting the engine together said that there was no need to key the crank/sprocket/pulley and because of this the revs were kept to a very conservative 8500rpm. At 8500 the power was still rising so there is certainly more power to be had if I get it keyed. Anyway other than the enormously disappointing 245 bhp and 166.2 lbft of torque the engine is a sweet as a nut. Steve G stood a £1 coin on the engine and it just sat there, it really is very very smooth. It's really drivable and still goes like a rocket.
So what have I learnt?
1,Should have discussed compression ratio with parts suppliers
2,I think using the C400 airbox along with smaller filter has restricted airflow
3,The 45 Jenveys should have been 48's and even better SBD's tapered T'B's.
4, key the crank/sprocket/pulley
The IVA is two weeks today…
Jason
To be fair thats still bloody impressive. Especially that you can stand £1 on the engine shows you built the engine extremely well. The first thing the Steve’s did was to check the compression ratio to see if it suited the plugs. It was found to be 190 psi give or take 5 on all cylinders and at that point the figure of 240 bhp was mentioned... I think mine is a compression ratio on 10.8 ish and Caterhams R500 is 12 ish. All very strange because the head was done by the same guy who does the R500 heads and as far as I aware there is only one set of Arrow rods and Omega pistons available for this engine. All I can think of is that the head guy also skims the caterham heads or more likely there is in fact other pistons available that change the compression ratio and if thats true then I'm going to be far from chuffed with the suppliers as they knew what I was trying to get. I'll find out.The advice I took when putting the engine together said that there was no need to key the crank/sprocket/pulley and because of this the revs were kept to a very conservative 8500rpm. At 8500 the power was still rising so there is certainly more power to be had if I get it keyed. Anyway other than the enormously disappointing 245 bhp and 166.2 lbft of torque the engine is a sweet as a nut. Steve G stood a £1 coin on the engine and it just sat there, it really is very very smooth. It's really drivable and still goes like a rocket.
So what have I learnt?
1,Should have discussed compression ratio with parts suppliers
2,I think using the C400 airbox along with smaller filter has restricted airflow
3,The 45 Jenveys should have been 48's and even better SBD's tapered T'B's.
4, key the crank/sprocket/pulley
The IVA is two weeks today…
Jason
Edited by Purespeed on Tuesday 8th February 18:22
It may be worth a quick call to Minister to see what compression ratio and parts they use on the C400 race engines.
If your going down the TB route I would suggest looking at Active Power throttles which increase airflow by ~10% over Jenvey. They see very good gains on all engines when back to back tested and mapped on the same engine vs Jenveys etc.
Post some pics up when the car is fully built and get yourself booked in for some trackdays / sprints this year!
Active Power throttle bodies are to be avoided and do not give good results
And this was the advice from a well known rolling road specialist, who has seen it all on the dyno
His advice was the best throttle bodies on the market are SBD's high spec throttle bodies
And after biting the bullet and buying some i would have to agree so far the quality is 1st class
And this was the advice from a well known rolling road specialist, who has seen it all on the dyno
His advice was the best throttle bodies on the market are SBD's high spec throttle bodies
And after biting the bullet and buying some i would have to agree so far the quality is 1st class
MadHatter7 said:
Active Power throttle bodies are to be avoided and do not give good results
And this was the advice from a well known rolling road specialist, who has seen it all on the dyno
His advice was the best throttle bodies on the market are SBD's high spec throttle bodies
And after biting the bullet and buying some i would have to agree so far the quality is 1st class
I beg to differ, Back to back independant test with one of the UK's best known engine builders produced solid gains on a range of engines. And this was the advice from a well known rolling road specialist, who has seen it all on the dyno
His advice was the best throttle bodies on the market are SBD's high spec throttle bodies
And after biting the bullet and buying some i would have to agree so far the quality is 1st class
Gassing Station | Caterham | Top of Page | What's New | My Stuff