What Engine for 500BHP
Discussion
I agree with Stevie and check your exhaust pressure, but I feel lowering the CR was the wrong way to go, too late for that though.
My thoughts are N/A cams do make eventual power, but are slow to spool, they're a bit pipe n slippers. You could maybe play around with the timing of them or fit some with a better profile.
My thoughts are N/A cams do make eventual power, but are slow to spool, they're a bit pipe n slippers. You could maybe play around with the timing of them or fit some with a better profile.
stevieturbo said:
turbonutter said:
Its about 100BHP down on what I had before with 1.3bar boost, but TBH that was maybe too much. Its very nice to drive now, as we have the boost mapped v/s rpm, throttle & gear. In fact its better than before with the extra power.
Still thinking of going with a smaller turbo, to get it to spool faster, as on the RR we didnt hit the boost target until 4700rpm & on the road its 500-750 rpm later than that.
Thinking of a GT3076R, with a tial turbine housing, as that will fit to my existing exhaust & boost pipes etc with no modifications. Looking at the turbine flows, the 3076 1.06ar housing flows the same as my current housing, so shouldnt choke the engine any worse than now & so should spool faster and still give me 500BHP... This needs investigating though...
IMO weld a fitting onto the manifold pre-turbo and see what pre-turbine pressure is like.Still thinking of going with a smaller turbo, to get it to spool faster, as on the RR we didnt hit the boost target until 4700rpm & on the road its 500-750 rpm later than that.
Thinking of a GT3076R, with a tial turbine housing, as that will fit to my existing exhaust & boost pipes etc with no modifications. Looking at the turbine flows, the 3076 1.06ar housing flows the same as my current housing, so shouldnt choke the engine any worse than now & so should spool faster and still give me 500BHP... This needs investigating though...
IMO there is no way it can be high or choking as you suggest, yet still spool so slowly, and when using relatively low boost.
I'm sure you've said before anyway, but what turbo and turbine housing are on it now ?
The data below is from the same pull on the rolling road that the power graph is from.. The Exhaust pressure is the same when on the road...
Turbo is a GT3582R with 0.82a/r turbine housing
Edited by turbonutter on Thursday 29th October 17:27
Can you show boost and ex manifold pressure on same screen, and same scaling only ?
It's very hard to make out any units or scaling on that screenshot.
Wherever your cursor is says manifold pressure is 40 and exhaust 86 ?
None of those units make any sense.
Edit.
I presume the scaling on the left covers both ? ie boost is around 180 or so ? so EGBP around 240 ?
I guess that's 0.8bar positive, and 1.4bar positive ?
If you want a smoother graph, either mechanically filter it, or I'm sure you can filter that channel in the log viewer.
Given how laggy it appears to be I'm surprised EGBP is that high, but in real terms it isnt so high it's of any concern at all.
It's very hard to make out any units or scaling on that screenshot.
Wherever your cursor is says manifold pressure is 40 and exhaust 86 ?
None of those units make any sense.
Edit.
I presume the scaling on the left covers both ? ie boost is around 180 or so ? so EGBP around 240 ?
I guess that's 0.8bar positive, and 1.4bar positive ?
If you want a smoother graph, either mechanically filter it, or I'm sure you can filter that channel in the log viewer.
Given how laggy it appears to be I'm surprised EGBP is that high, but in real terms it isnt so high it's of any concern at all.
Edited by stevieturbo on Thursday 29th October 17:59
stevieturbo said:
Can you show boost and ex manifold pressure on same screen, and same scaling only ?
It's very hard to make out any units or scaling on that screenshot.
Wherever your cursor is says manifold pressure is 40 and exhaust 86 ?
None of those units make any sense.
Edit.
I presume the scaling on the left covers both ? ie boost is around 180 or so ? so EGBP around 240 ?
I guess that's 0.8bar positive, and 1.4bar positive ?
If you want a smoother graph, either mechanically filter it, or I'm sure you can filter that channel in the log viewer.
Given how laggy it appears to be I'm surprised EGBP is that high, but in real terms it isnt so high it's of any concern at all.
Ok Here it is again:It's very hard to make out any units or scaling on that screenshot.
Wherever your cursor is says manifold pressure is 40 and exhaust 86 ?
None of those units make any sense.
Edit.
I presume the scaling on the left covers both ? ie boost is around 180 or so ? so EGBP around 240 ?
I guess that's 0.8bar positive, and 1.4bar positive ?
If you want a smoother graph, either mechanically filter it, or I'm sure you can filter that channel in the log viewer.
Given how laggy it appears to be I'm surprised EGBP is that high, but in real terms it isnt so high it's of any concern at all.
Edited by stevieturbo on Thursday 29th October 17:59
MAP, Boost Target & EBP are 50-300kpa
rpm 0-7000
throttle 0-100%
And I have stuck the cursor where you can see it. 6950rpm - Map =195kpa (0.95bar) EBP = 257kpa (1.57bar) so pretty close to what you interpreted from the first graph.
What would you consider too high for Exhaust pressure?
turbonutter said:
Ok Here it is again:
MAP, Boost Target & EBP are 50-300kpa
rpm 0-7000
throttle 0-100%
And I have stuck the cursor where you can see it. 6950rpm - Map =195kpa (0.95bar) EBP = 257kpa (1.57bar) so pretty close to what you interpreted from the first graph.
What would you consider too high for Exhaust pressure?
At that point, you're only around 1.3:1 PR. Really not bad at all, and in no way whatsoever is that choking the engine.MAP, Boost Target & EBP are 50-300kpa
rpm 0-7000
throttle 0-100%
And I have stuck the cursor where you can see it. 6950rpm - Map =195kpa (0.95bar) EBP = 257kpa (1.57bar) so pretty close to what you interpreted from the first graph.
What would you consider too high for Exhaust pressure?
Plenty of people running much much higher than that. Some run as high as 3:1 at times, I personally wouldnt want to see over 2:1 although a lot will depend on the characteristics of the system too.
ie super fast spooling and very torquey...I'd suffer a higher PR to achieve that or if it was all out power at the top, I'd obviously want much much lower PR but then probably would sacrifice some spool etc at the lower end.
If you can get a turbo with similar turbine flow and much smaller lighter compressor, it should spool up a lot faster, but still be efficient on the turbine side too.
Maybe try and pick up a GT30 second hand ? Although probably need to buy the turbine hosing new to suit your V-Band unless you're lucky to find one.
On the subject of the cam, all I really think I know is that for boosted applications you need little to no overlap between intake and exhaust valve opening to allow the turbo/supercharger to actually pressurise the cylinder, whereas NA you need the overlap to help keep the air flowing. I would look into seeing if you can get a CAM designed for boost IMO, will improve the engine a lot.
R8VXF said:
On the subject of the cam, all I really think I know is that for boosted applications you need little to no overlap between intake and exhaust valve opening to allow the turbo/supercharger to actually pressurise the cylinder, whereas NA you need the overlap to help keep the air flowing. I would look into seeing if you can get a CAM designed for boost IMO, will improve the engine a lot.
That's completely incorrect. You treat a performance turbo engine with a sizeable turbo just like you would a performance NA when it comes to cams.Neil the cams in your engine are pathetic! It must be like driving a car with small electric motor - it gets there eventually, just very smoothly and slowly. The tricky bit would be introducing more power without it happening all at once and throwing you sideways, so I guess a mild cam upgrade coupled with your trick boost control would work well. It would be too easy to let loose with big power and make a car which is vicious to drive.
stevieturbo said:
Do you have adjustable camwheels ? And can they be adjusted easily ?
Rather than spending money on cams, it could be worth playing with them on the dyno.
Stevie - the cams are not easily adjustable. The cam wheel/cam connection is a taper, with no key, so could be adjusted, but not something easily done, especially time wise on a RR.Rather than spending money on cams, it could be worth playing with them on the dyno.
Evoluzione said:
That's completely incorrect. You treat a performance turbo engine with a sizeable turbo just like you would a performance NA when it comes to cams.
Neil the cams in your engine are pathetic! It must be like driving a car with small electric motor - it gets there eventually, just very smoothly and slowly. The tricky bit would be introducing more power without it happening all at once and throwing you sideways, so I guess a mild cam upgrade coupled with your trick boost control would work well. It would be too easy to let loose with big power and make a car which is vicious to drive.
Must just be a supercharger thing then Neil the cams in your engine are pathetic! It must be like driving a car with small electric motor - it gets there eventually, just very smoothly and slowly. The tricky bit would be introducing more power without it happening all at once and throwing you sideways, so I guess a mild cam upgrade coupled with your trick boost control would work well. It would be too easy to let loose with big power and make a car which is vicious to drive.
Evoluzione said:
R8VXF said:
On the subject of the cam, all I really think I know is that for boosted applications you need little to no overlap between intake and exhaust valve opening to allow the turbo/supercharger to actually pressurise the cylinder, whereas NA you need the overlap to help keep the air flowing. I would look into seeing if you can get a CAM designed for boost IMO, will improve the engine a lot.
That's completely incorrect. You treat a performance turbo engine with a sizeable turbo just like you would a performance NA when it comes to cams.Neil the cams in your engine are pathetic! It must be like driving a car with small electric motor - it gets there eventually, just very smoothly and slowly. The tricky bit would be introducing more power without it happening all at once and throwing you sideways, so I guess a mild cam upgrade coupled with your trick boost control would work well. It would be too easy to let loose with big power and make a car which is vicious to drive.
More power I dont need! If I wind up the boost to 1.5 bar , I would expect to see around 600BHP, which is more than the rest of the driveline can handle. So as the thread title, I have now decided to stick with around 500BHP, what I am looking for is to get the boost earlier to get better driveability...
All suggestions are welcome...
stevieturbo said:
If you can get a turbo with similar turbine flow and much smaller lighter compressor, it should spool up a lot faster, but still be efficient on the turbine side too.
Maybe try and pick up a GT30 second hand ? Although probably need to buy the turbine hosing new to suit your V-Band unless you're lucky to find one.
The GT30 1.06 a/r housing has pretty much the same flow as the gt35 0.82 housing, so that should work. There is one for sale, with a tial housing in the USA now, but the guy selling it dosent know what a/r the housing is!!!Maybe try and pick up a GT30 second hand ? Although probably need to buy the turbine hosing new to suit your V-Band unless you're lucky to find one.
turbonutter said:
Evoluzione said:
R8VXF said:
On the subject of the cam, all I really think I know is that for boosted applications you need little to no overlap between intake and exhaust valve opening to allow the turbo/supercharger to actually pressurise the cylinder, whereas NA you need the overlap to help keep the air flowing. I would look into seeing if you can get a CAM designed for boost IMO, will improve the engine a lot.
That's completely incorrect. You treat a performance turbo engine with a sizeable turbo just like you would a performance NA when it comes to cams.Neil the cams in your engine are pathetic! It must be like driving a car with small electric motor - it gets there eventually, just very smoothly and slowly. The tricky bit would be introducing more power without it happening all at once and throwing you sideways, so I guess a mild cam upgrade coupled with your trick boost control would work well. It would be too easy to let loose with big power and make a car which is vicious to drive.
More power I dont need! If I wind up the boost to 1.5 bar , I would expect to see around 600BHP, which is more than the rest of the driveline can handle. So as the thread title, I have now decided to stick with around 500BHP, what I am looking for is to get the boost earlier to get better driveability...
All suggestions are welcome...
What is the power curve like on a stock engine thats not turbocharged?
Despite the lower CR Id expect your power curve to be better than the NA everywhere and just have it increase when boost comes on.... if the stock engine doesn't have much power low down its going to be hard to change that dynamic pre turbo spool.
Despite the lower CR Id expect your power curve to be better than the NA everywhere and just have it increase when boost comes on.... if the stock engine doesn't have much power low down its going to be hard to change that dynamic pre turbo spool.
turbonutter said:
Stevie - the cams are not easily adjustable. The cam wheel/cam connection is a taper, with no key, so could be adjusted, but not something easily done, especially time wise on a RR.
Can you get vernier pulleys for them though ? to make it easily adjustable ?R8VXF said:
On the subject of the cam, all I really think I know is that for boosted applications you need little to no overlap between intake and exhaust valve opening to allow the turbo/supercharger to actually pressurise the cylinder, whereas NA you need the overlap to help keep the air flowing. I would look into seeing if you can get a CAM designed for boost IMO, will improve the engine a lot.
It really depends. If the system does see much higher pressure in the exhaust manifold, then yes. You dont really want any overlap for obvious reasons. But as it also depends how well heads etc flow, rpm's etc etc there is no easy answer.Well there is, cams with little or no overlap will always be safe and capable of great drive ability and good power. The worst thing you'll ever do on a turbo engine is go too big with the cams. Usually that just hurts low end drive ability, spool, torque.....all for very little if any real gain up top, and can just shift the power band upwards, often without actually making you go any faster.
the more efficient you can make the build, the closer to 1:1 EGBP vs Manifold pressure...the more you can push with the cams without worry of it turning the car into a piece of s
t to drive.His cams are fine though, it isnt an all out race engine, but it would be nice to be able to play with the timing a bit if it could be done easily.
Maybe advance the exhaust cam a bit to try, might make it spool a little earlier.
But the GT30 sounds like a good plan.
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