Verification of the 4.2 Rebuild by APM
Discussion
After 3,000 miles of running in and a track day, to loosen it up a little more
, I took the Cerb down to Surrey Rolling road for my Power Testing for verification for the TVR Sprint Challenge algorythm.
I have to say that the Cerb has been running at an amazing pace since the rebuild, both in terms of low down power and smooth pick-up and ability to rev now that it has been bedded in.
The result is a max of 366.1 BHP, 320 fFtLb, run in 3rd gear. The three runs were pretty much there.
There is no ECU modification, the only changes have been 4.5 manifolds which are Ceramic coated and do make a big difference to getting heat out of the engine bay, it runs at sub 80 degrees and gets up to about 85 on track days, Aluminium rad helps.
Looking at the recent & historical threads "if it was run in 4th", as some RRds have done and do, there seems to be about a 10% advantage in the transmission wastage which would equate my 3rd gear result to the 400 bhp all the 4.5 boys keep banging on about.
I'll post the Dynamics Graph when I work out how to do it. It is pretty much a straight line of bhp to revs, starting to round at 5500, torque is around the 300 mark from 3200 until 6400.
Frankly I am very very happy with Andy's rebuild and the dynamics keep my comfort that on a circuit, the 4.2 having a straight line graph, keeps me on the boil and I don't have to worry about gear shifting around any troughs in the power curve.
Attention to detail is what has given this engine this output, I assume this is a high result for what is to all intensive purposes a standard 4.2.
Well done Andy, top job mate.
John
, I took the Cerb down to Surrey Rolling road for my Power Testing for verification for the TVR Sprint Challenge algorythm. I have to say that the Cerb has been running at an amazing pace since the rebuild, both in terms of low down power and smooth pick-up and ability to rev now that it has been bedded in.
The result is a max of 366.1 BHP, 320 fFtLb, run in 3rd gear. The three runs were pretty much there.
There is no ECU modification, the only changes have been 4.5 manifolds which are Ceramic coated and do make a big difference to getting heat out of the engine bay, it runs at sub 80 degrees and gets up to about 85 on track days, Aluminium rad helps.
Looking at the recent & historical threads "if it was run in 4th", as some RRds have done and do, there seems to be about a 10% advantage in the transmission wastage which would equate my 3rd gear result to the 400 bhp all the 4.5 boys keep banging on about.
I'll post the Dynamics Graph when I work out how to do it. It is pretty much a straight line of bhp to revs, starting to round at 5500, torque is around the 300 mark from 3200 until 6400.
Frankly I am very very happy with Andy's rebuild and the dynamics keep my comfort that on a circuit, the 4.2 having a straight line graph, keeps me on the boil and I don't have to worry about gear shifting around any troughs in the power curve.
Attention to detail is what has given this engine this output, I assume this is a high result for what is to all intensive purposes a standard 4.2.
Well done Andy, top job mate.
John
Sounds like a good result to me, I went down to SRR for the Cerb Rolling Road day the other week. Was very pleased with 365.7 which Charlie said was the highest 4.2 (Standard) he could recall having run, seems you have beaten me 
.........just 
Would love to see your graph for comparison, will try to get mine scanned and posted up this afternoon.
Oh best I give thanks to Steve Howard at Euphoria as car was fresh from his fettling hands
.........just Would love to see your graph for comparison, will try to get mine scanned and posted up this afternoon.
Oh best I give thanks to Steve Howard at Euphoria as car was fresh from his fettling hands
jonnyw said:
Your one seems to have a dull spot and then gets back on with it, can you feel that on the road or did the tyres try and clim out the rollers?
Can't say I really notice it on the road, car is pretty grumpy pulling from under 2 revs and really smooths out over 3k but always attributed that to the nature of the engine, the power is so much further up the rev range than I was used to with the Chimaera (not had car long so still getting used to it). I have a chart from another run and it is pretty jumpy the whole way along so probably more to do with the run than anything else.
Got to big up the little 4.2 though, really very good for their quoted numbers and right up there a lot of the time with the 4.5's.
Nice one John-well done Andy that looks excellent. I have to admit to being a little dissapointed as my last years rebuild with another well known company has released only 336 bhp but it does have more torque. It would be interesting to get our cars side by side and have ago after North Weald next weekend and see how they go in a straight line.
Jes
Jes
trackcar said:
I was emailing Andy about this engine the other night .. he asked me if it was a good output .. my response was that it was a blinking excellent output, that man certainly seems to know the tricks
Hey look Joolz.. I even did it in 3rd
Did you ask Andy about the fueling John?
jesfirth said:
Nice one John-well done Andy that looks excellent. I have to admit to being a little dissapointed as my last years rebuild with another well known company has released only 336 bhp but it does have more torque. It would be interesting to get our cars side by side and have ago after North Weald next weekend and see how they go in a straight line.
Jes
I may be missing something here, but should the algorithm not favour you (in the most minute way, but any advantage is an advantage)
Charlie, yes it is pretty much on the limit but within tollerance, Andy has tried with what we've got, the issue is the ECU's limit on breathing and fuel. The Emerald angle is a route to get it over the 400bhp mark and richen the mixture but it is so quick at the moment we have decided to keep it as it is for the time being. I suppose the ECU is the limit to BHP at the moment, the car is obviously capable of breathing harder!
With regard to the algorithm, I will be penalised for 16.1 BHP over standard, which won't be much.
Jes, a straight line drag will be interesting down the runway but what about my 15 stone to your 11? Race you for a burger!
All the best
John
With regard to the algorithm, I will be penalised for 16.1 BHP over standard, which won't be much.
Jes, a straight line drag will be interesting down the runway but what about my 15 stone to your 11? Race you for a burger!
All the best
John
jonnyw said:
With regard to the algorithm, I will be penalised for 16.1 BHP over standard,
John
6 bhp over std surely? the 4.2 was rated at 360hp wasn't it? been that long since i saw a sales sheet for the 4.2 i can't quite remember but i *thought* it was 350 for sp6, 360 for 4.2, 420 for 4.5 ... ?
Gassing Station | Cerbera | Top of Page | What's New | My Stuff