scoobyclinics turbo's just got billet I mean better!
22 December 2011, 08:34 PM
#3272
Engine Specialist
My experience, which is much smaller than Kev's or Martyn's on the DD at my place has been that you cannot definitively say what the difference in spool would be without logging that individual car, which in your experience Shaun may be 300rpm in that gear, but certainly won't be the same as the next car that is run.
After-all spool is dictated by simple fluid dynamics in terms of exhaust flow and pressure vs turbine and compressor flow and inertia characteristics, but in practice it is very complex in it's effects.
Looking at it simply, a simple difference in manifold and up-pipe pressure at a given cfm and temperature will give a very different spool-to-rpm point, i.e. second gear full throttle at 4000rpm might generate 360cfm flow at a temperature of 550c, whereas 4000rpm in fifth gear might generate 360cfm at 750c lets say. The fifth gear pull will obviously generate a faster velocity turbine gas flow which will spool the turbo faster. However the time in gear and the generation of exhaust gas flow and temperature will change and so the spool will change, it's inevitable. Albeir second gear is unlikely to generate the same exhaust gas cfm as the turbo spools slower and heat generation is obviously lower because the engine has to do less work etc etc.
I'd say based on just this that anywhere from no change in rpm spool vs the dyno, (if ramp rate equals realistic in gear acceleration time), to a large difference in spool is quite realistic, on a big turbo 1000rpm is very possibly.
I always map in a higher gear to give a best spool case scenario whilst trying to work within the dynos most accurate roller speed range, otherwise I think the wastegate duty numbers applied will be a little large for the higher gears, (putting in-gear boost compensation aside).
Don't forget that the dynos ramp rate is static, where as a road based scenario has other effects like aerodynamic exponential resistance to make the engine work harder.
Graham
After-all spool is dictated by simple fluid dynamics in terms of exhaust flow and pressure vs turbine and compressor flow and inertia characteristics, but in practice it is very complex in it's effects.
Looking at it simply, a simple difference in manifold and up-pipe pressure at a given cfm and temperature will give a very different spool-to-rpm point, i.e. second gear full throttle at 4000rpm might generate 360cfm flow at a temperature of 550c, whereas 4000rpm in fifth gear might generate 360cfm at 750c lets say. The fifth gear pull will obviously generate a faster velocity turbine gas flow which will spool the turbo faster. However the time in gear and the generation of exhaust gas flow and temperature will change and so the spool will change, it's inevitable. Albeir second gear is unlikely to generate the same exhaust gas cfm as the turbo spools slower and heat generation is obviously lower because the engine has to do less work etc etc.
I'd say based on just this that anywhere from no change in rpm spool vs the dyno, (if ramp rate equals realistic in gear acceleration time), to a large difference in spool is quite realistic, on a big turbo 1000rpm is very possibly.
I always map in a higher gear to give a best spool case scenario whilst trying to work within the dynos most accurate roller speed range, otherwise I think the wastegate duty numbers applied will be a little large for the higher gears, (putting in-gear boost compensation aside).
Don't forget that the dynos ramp rate is static, where as a road based scenario has other effects like aerodynamic exponential resistance to make the engine work harder.
Graham
22 December 2011, 08:41 PM
#3273
Scooby Regular
And well put BTW
Martyn
23 December 2011, 09:39 AM
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My experience, which is much smaller than Kev's or Martyn's on the DD at my place has been that you cannot definitively say what the difference in spool would be without logging that individual car, which in your experience Shaun may be 300rpm in that gear, but certainly won't be the same as the next car that is run.
After-all spool is dictated by simple fluid dynamics in terms of exhaust flow and pressure vs turbine and compressor flow and inertia characteristics, but in practice it is very complex in it's effects.
Looking at it simply, a simple difference in manifold and up-pipe pressure at a given cfm and temperature will give a very different spool-to-rpm point, i.e. second gear full throttle at 4000rpm might generate 360cfm flow at a temperature of 550c, whereas 4000rpm in fifth gear might generate 360cfm at 750c lets say. The fifth gear pull will obviously generate a faster velocity turbine gas flow which will spool the turbo faster. However the time in gear and the generation of exhaust gas flow and temperature will change and so the spool will change, it's inevitable. Albeir second gear is unlikely to generate the same exhaust gas cfm as the turbo spools slower and heat generation is obviously lower because the engine has to do less work etc etc.
I'd say based on just this that anywhere from no change in rpm spool vs the dyno, (if ramp rate equals realistic in gear acceleration time), to a large difference in spool is quite realistic, on a big turbo 1000rpm is very possibly.
I always map in a higher gear to give a best spool case scenario whilst trying to work within the dynos most accurate roller speed range, otherwise I think the wastegate duty numbers applied will be a little large for the higher gears, (putting in-gear boost compensation aside).
Don't forget that the dynos ramp rate is static, where as a road based scenario has other effects like aerodynamic exponential resistance to make the engine work harder.
Graham
After-all spool is dictated by simple fluid dynamics in terms of exhaust flow and pressure vs turbine and compressor flow and inertia characteristics, but in practice it is very complex in it's effects.
Looking at it simply, a simple difference in manifold and up-pipe pressure at a given cfm and temperature will give a very different spool-to-rpm point, i.e. second gear full throttle at 4000rpm might generate 360cfm flow at a temperature of 550c, whereas 4000rpm in fifth gear might generate 360cfm at 750c lets say. The fifth gear pull will obviously generate a faster velocity turbine gas flow which will spool the turbo faster. However the time in gear and the generation of exhaust gas flow and temperature will change and so the spool will change, it's inevitable. Albeir second gear is unlikely to generate the same exhaust gas cfm as the turbo spools slower and heat generation is obviously lower because the engine has to do less work etc etc.
I'd say based on just this that anywhere from no change in rpm spool vs the dyno, (if ramp rate equals realistic in gear acceleration time), to a large difference in spool is quite realistic, on a big turbo 1000rpm is very possibly.
I always map in a higher gear to give a best spool case scenario whilst trying to work within the dynos most accurate roller speed range, otherwise I think the wastegate duty numbers applied will be a little large for the higher gears, (putting in-gear boost compensation aside).
Don't forget that the dynos ramp rate is static, where as a road based scenario has other effects like aerodynamic exponential resistance to make the engine work harder.
Graham
Hi,
spot on.
every car behaves differently there are so many variables and as we have researched and developed a range of turbos on our dyno we have data logged the spool/boost both on the dyno and on the road in various gears on many cars with different set ups.
What Shaun has found on his car may be correct but it is just one car we see hundreds.
Cheers
Kev
23 December 2011, 02:42 PM
#3276
Scooby Regular
Martyn,
Perhaps I worded my original response badly.... but until you or anyone else explains to me, why what I have said (as that is what I understand) is not correct - then my understanding will be the same.
Perhaps you need to re-read some of your own posts.... you do make a habit of coming across as a condescending **** at times, thinly masked with the odd "lol" or "
". Which is quite strange as you have only recently given me information on DD RR stuff off-line, answering a number of queries and questions.
Perhaps that's the "banter" and I've read it the wrong way.
Graham,
Thank you for taking the time to explain the detail. I really do appreciate that.
I understand what you're saying, but to underline I had already stated the asumption that the gear would be the same and assuming a DD RR was being used, the ramp rate is the same on all DD RR's. OK I appreciate the "other" car was ran in 3rd, but that's on a 5sp so still a 1:1 gear ratio, so load due to gearing should be nearly the same as 4th on a 6sp (unless I have really got that one wrong which is possible lol ?).
Again, thanks for taking the time to explain.
Kev,
I actually find this interesting.... but I can only apologise for diverting the thread mate.
Perhaps I worded my original response badly.... but until you or anyone else explains to me, why what I have said (as that is what I understand) is not correct - then my understanding will be the same.
Perhaps you need to re-read some of your own posts.... you do make a habit of coming across as a condescending **** at times, thinly masked with the odd "lol" or "
". Which is quite strange as you have only recently given me information on DD RR stuff off-line, answering a number of queries and questions. Perhaps that's the "banter" and I've read it the wrong way.
Graham,
Thank you for taking the time to explain the detail. I really do appreciate that.
I understand what you're saying, but to underline I had already stated the asumption that the gear would be the same and assuming a DD RR was being used, the ramp rate is the same on all DD RR's. OK I appreciate the "other" car was ran in 3rd, but that's on a 5sp so still a 1:1 gear ratio, so load due to gearing should be nearly the same as 4th on a 6sp (unless I have really got that one wrong which is possible lol ?).
Again, thanks for taking the time to explain.
Kev,
I actually find this interesting.... but I can only apologise for diverting the thread mate.
23 December 2011, 02:56 PM
#3277
Scooby Regular
Martyn,
Perhaps I worded my original response badly.... but until you or anyone else explains to me, why what I have said (as that is what I understand) is not correct - then my understanding will be the same.
Perhaps you need to re-read some of your own posts.... you do make a habit of coming across as a condescending **** at times, thinly masked with the odd "lol" or " ". Which is quite strange as you have only recently given me information on DD RR stuff off-line, answering a number of queries and questions.
Perhaps that's the "banter" and I've read it the wrong way.
Perhaps I worded my original response badly.... but until you or anyone else explains to me, why what I have said (as that is what I understand) is not correct - then my understanding will be the same.
Perhaps you need to re-read some of your own posts.... you do make a habit of coming across as a condescending **** at times, thinly masked with the odd "lol" or "
". Which is quite strange as you have only recently given me information on DD RR stuff off-line, answering a number of queries and questions. Perhaps that's the "banter" and I've read it the wrong way.
, take a quick look at the gearbox ratio charts which are around Shaun and you'll find that on a 5 speed box, 4th gear is the one closest to a 1:1 ratio.Martyn
23 December 2011, 03:51 PM
#3278
Engine Specialist
I understand what you're saying, but to underline I had already stated the asumption that the gear would be the same and assuming a DD RR was being used, the ramp rate is the same on all DD RR's. OK I appreciate the "other" car was ran in 3rd, but that's on a 5sp so still a 1:1 gear ratio, so load due to gearing should be nearly the same as 4th on a 6sp (unless I have really got that one wrong which is possible lol ?).
The other big thing that I really haven't explained fully is the transition of acceleration that you get on the road vs on the dyno. You'll notice that the dyno has a fairly steady rate of acceleration, aside from when you go from no boost too full boost where it tries to maintain the ramp rate. This isn't at all the case on the road where acceleration rapidly changes as you come on boost and then very quickly reduces, (especially in 4th/5th or 6th), as aerodynamic resistance takes hold. So the acceleration in gear on the road will be very different. Hence the reason a car should always be finished off on the road!
More restrictive exhausts produce much greater differences in spool on the road vs dyno as well especially in the higher gears where EGTs are at their highest.
I don't know whether that helps anymore!!
Graham
23 December 2011, 08:50 PM
#3279
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Shaun, I think the short answer for your results differing from the norm is simply that you have mainly been testing small twin scroll turbos, these spool very quickly so the difference between road and rollers will be much closer.
23 December 2011, 09:08 PM
#3282
ly ............ Santa does do Billet Turbos but unfortunetly he passes through Scotland first
23 December 2011, 09:30 PM
#3284
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Can't fault Kevs service, turbos arrived at SC from Blouch on Wednesday, he held the delivery driver captive until he printed and applied my address label and they went back out to me on the same van. 10/10 for effort Particularly at this time of year, these van drivers don't normally hang about !
Particularly at this time of year, these van drivers don't normally hang about !
23 December 2011, 09:43 PM
#3285
Couriers are a law to themselves, i had a package go missing for near a week, turned out it was held in depot 80 miles away as there was no contact number on it, gave the number to the office girl, and it was deliverd next day... but i never got a phone call..wtf?
24 December 2011, 08:24 AM
#3288
Scooby Regular
Can't fault Kevs service, turbos arrived at SC from Blouch on Wednesday, he held the delivery driver captive until he printed and applied my address label and they went back out to me on the same van. 10/10 for effort Particularly at this time of year, these van drivers don't normally hang about !
Particularly at this time of year, these van drivers don't normally hang about ! Oh **** no, that's the invoice
Gawd bless im !
Turbos look interesting, GT35 variety this time ?
Martyn
24 December 2011, 09:43 AM
#3289
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Kevs and the crew at scooby clinic bend over backwards to help us guys out on ukscoobies and have never let us down with help or advice great service up there.
Last edited by scoobybry!; 24 December 2011 at 09:45 AM.
24 December 2011, 10:18 AM
#3290
Did I hear mention of a functioning SC38 above?
I have nothing to add to the luminaries above, aside than to say I would agree with Kev's comment that a car always needs to be finished at least on the road. I had a world of problems with a mapper who refused to finish my car off on the road, where it overboosted dramatically.
Its history now, but always a road map to finish.
My Sc36 boosts much better than its graph on road too.
I have nothing to add to the luminaries above, aside than to say I would agree with Kev's comment that a car always needs to be finished at least on the road. I had a world of problems with a mapper who refused to finish my car off on the road, where it overboosted dramatically.
Its history now, but always a road map to finish.
My Sc36 boosts much better than its graph on road too.
24 December 2011, 12:10 PM
#3291
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Perhaps the turbos spooling in the box scared her off These are Billet 30R's but with a bit of my own porting of the housings. The interesting part of these compressor wheels is that 1 - they are lighter and have a lower flow obstruction CSA than the cast versions and 2 - they have an extended tip design so whilst the compressor rotor backplate OD is 75mm in this case, the blades actually extend to 80mm, thus you achieve a flow rate approaching GT35R capacity but lower inertia that improves spool up on the GT30R. Its a proper win-win
I can post pics to show this clearer if Kev doesn't mind this sort of detail going public?
Last edited by Andy.F; 24 December 2011 at 12:14 PM.
24 December 2011, 01:01 PM
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I was promised a blow up doll with mine but she seemed to escape from the packaging somehow Perhaps the turbos spooling in the box scared her off
These are Billet 30R's but with a bit of my own porting of the housings. The interesting part of these compressor wheels is that 1 - they are lighter and have a lower flow obstruction CSA than the cast versions and 2 - they have an extended tip design so whilst the compressor rotor backplate OD is 75mm in this case, the blades actually extend to 80mm, thus you achieve a flow rate approaching GT35R capacity but lower inertia that improves spool up on the GT30R. Its a proper win-win
I can post pics to show this clearer if Kev doesn't mind this sort of detail going public?
Perhaps the turbos spooling in the box scared her off These are Billet 30R's but with a bit of my own porting of the housings. The interesting part of these compressor wheels is that 1 - they are lighter and have a lower flow obstruction CSA than the cast versions and 2 - they have an extended tip design so whilst the compressor rotor backplate OD is 75mm in this case, the blades actually extend to 80mm, thus you achieve a flow rate approaching GT35R capacity but lower inertia that improves spool up on the GT30R. Its a proper win-win
I can post pics to show this clearer if Kev doesn't mind this sort of detail going public?
Hi,
no problem, post away.
Merry Xmas to all.
Same pic as last year I know but its a bit last minute.
cheers
Kev
24 December 2011, 02:01 PM
#3295
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Take it you'll be using the magical aid of NOS to spool these puppies up? Might be fast spooling but each one running off 1800cc, 5k rpm full boost perhaps?
But 5k onwards.... Wow
But 5k onwards.... Wow
24 December 2011, 02:39 PM
#3296
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I hope these spool a bit quicker than the GT30R's that were on there a few months back, they made 1 bar at a smidge over 4k, 1 bar is still like 600bhp so things start happening quickly after that and you certainly aint looking at the dials anymore
24 December 2011, 03:39 PM
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Wow, that is not bad going at all. Is that on just v power? Provided these spool and flow better than the standard SC range, will you be linking up with SC and supplying the 30R's with these fettled features?
24 December 2011, 04:10 PM
#3299
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My fettling will not affect the spool up, it should help a little at the top end but we are not talking big differences here, its just one of the many little tweeks that I add to my car!
The EG33 has shorter headers and different cam profiles from any 4 cyl engine so thats possibly where I score on spool up.
The EG33 has shorter headers and different cam profiles from any 4 cyl engine so thats possibly where I score on spool up.
24 December 2011, 04:32 PM
#3300
Well Andy your certainly getting me excited anout the GT30 billet
And Martyn even more with the thoughts of a Blow up doll spooling up and popping out of the box...
why is it now
when i think of Kev and the Clinic i will think of http://www.youtube.com/watch?v=Yu8b-03LQTg
And Martyn even more with the thoughts of a Blow up doll spooling up and popping out of the box...
why is it now
when i think of Kev and the Clinic i will think of http://www.youtube.com/watch?v=Yu8b-03LQTg
Last edited by kenc; 24 December 2011 at 04:39 PM.