Rolling road graph
Discussion
Hi,
Its Neal again with the engine holding back was my last thread.. but that got kind of other peoples problems so starting fresh. Got my 8 snapped valve springs done and back to the rollers and this is what I came away with.
Car is a rover v8 4.6 running around 8.0 compression. It has standard TVR 4.0 heads which I think just have double valve springs. The cam I am running is (cut and paste
)
DW252 Viper Cyclone
Rpm Range Idle-5500rpm
@.050" In.206 Ex.206
Lift-1.60 Rockers In;.433"Ex; .433"
Lobe Sep 108 degrees
Running 2x td04l turbos from a subaru impreza, im intercooled and a nice big bosch 044 fuel pump, larger saab 360cc red injectors @ 3bar.
This is the graph below seems to make the torque then drop off. Running 10psi on this graph and stopped there as the torque jumped to 490lbft. Not had chance to really drive the car yet due to weather but does it look like some kind of restriction or maybe Im just out of flow on those turbos??
Open to any suggestions (come on pumaracing
)
Its Neal again with the engine holding back was my last thread.. but that got kind of other peoples problems so starting fresh. Got my 8 snapped valve springs done and back to the rollers and this is what I came away with.
Car is a rover v8 4.6 running around 8.0 compression. It has standard TVR 4.0 heads which I think just have double valve springs. The cam I am running is (cut and paste
)DW252 Viper Cyclone
Rpm Range Idle-5500rpm
@.050" In.206 Ex.206
Lift-1.60 Rockers In;.433"Ex; .433"
Lobe Sep 108 degrees
Running 2x td04l turbos from a subaru impreza, im intercooled and a nice big bosch 044 fuel pump, larger saab 360cc red injectors @ 3bar.
This is the graph below seems to make the torque then drop off. Running 10psi on this graph and stopped there as the torque jumped to 490lbft. Not had chance to really drive the car yet due to weather but does it look like some kind of restriction or maybe Im just out of flow on those turbos??
Open to any suggestions (come on pumaracing
)
Pupp said:
Hope you've got some spare drive shafts lined up!
When I fist looked at that I thought the torque and power were reversed
Where did the ign advance end up under load?
Well just got back from a drive and gotta say its quick! Spins up very fast smoked the tyres in 3rd with a little press right the way to red line (sWhen I fist looked at that I thought the torque and power were reversed
Where did the ign advance end up under load?
t myself!) lol the way it gains speed is impressive now.Hi Pupp,
Dont know on ignition timing yet will have to get laptop out and have a look, will let you know
Simon says said:
Neal why the broken valve springs did/have you got coil binding going on or something? that torque 
tyre shredding springs to mind 
great car for when you retire you hardly need to stir that gearstick 
Think it was from my old engine I just didnt notice when I built this one up I just assumed they were fine, stupid i know but we learn. 8 were broken more than likely incorrect springs reverted back to TVR ones now seems fine. tyre shredding springs to mind great car for when you retire you hardly need to stir that gearstick stevieturbo said:
Sadly not much usable info on that graph.
Boost and fuelling would be nice.
Surely boost doesnt take as long as 4000rpm to peak ? The torque spike almost suggests that ?
It spools very quick but I didnt glance down I was watching the road..lol I will have to try again. Im sure we had some datalogs on the MS when we were doing the runs maybe this will show up more.Boost and fuelling would be nice.
Surely boost doesnt take as long as 4000rpm to peak ? The torque spike almost suggests that ?
Edited by stevieturbo on Monday 13th June 21:16
Max_Torque said:
Not sure on the graphs, but wow, 1980, talk about Old Skool....... ;-)
(more usefully, as mentioned ^^^, need boost pressure, AFR, ignition angle etc really to be able to make a better call on it)
old skool rocks (more usefully, as mentioned ^^^, need boost pressure, AFR, ignition angle etc really to be able to make a better call on it)
Will hunt for the log as above and see.Didnt know if the graphs looks odd but it certainly drives nice. Power tailing off at the top end that you can notice but one change again and your away. Just had a look at one of these turbos on my bench they really are small! how the hell can all that flow get through that exhaust housing
TBH, that graph makes it look laggy. Makes it look like you dont have stable boost.
As far as rpm's go. It's a RV8 with a very mild cam. So it isnt surprising it's dying off at the top end. That's just how they are. But depending on gearing, that might not be a problem. It certainly has the torque to make up for it.
It's unlikely it's down to the turbos seeing as a 2.0 turbo Impreza will happily rev to 7k+ making 300bhp at a push with one of those turbos.
The rover will never replicate that though.
The high torque output does show the potential you have though. Just looks like it needs some fine tuning to smooth it out. Unless perhaps there are just issues with the actual dyno run itself.
Or did they just not bother trying to dyno full throttle below 3-3500rpm ?
As far as rpm's go. It's a RV8 with a very mild cam. So it isnt surprising it's dying off at the top end. That's just how they are. But depending on gearing, that might not be a problem. It certainly has the torque to make up for it.
It's unlikely it's down to the turbos seeing as a 2.0 turbo Impreza will happily rev to 7k+ making 300bhp at a push with one of those turbos.
The rover will never replicate that though.
The high torque output does show the potential you have though. Just looks like it needs some fine tuning to smooth it out. Unless perhaps there are just issues with the actual dyno run itself.
Or did they just not bother trying to dyno full throttle below 3-3500rpm ?
stevieturbo said:
TBH, that graph makes it look laggy. Makes it look like you dont have stable boost.
As far as rpm's go. It's a RV8 with a very mild cam. So it isnt surprising it's dying off at the top end. That's just how they are. But depending on gearing, that might not be a problem. It certainly has the torque to make up for it.
It's unlikely it's down to the turbos seeing as a 2.0 turbo Impreza will happily rev to 7k+ making 300bhp at a push with one of those turbos.
The rover will never replicate that though.
The high torque output does show the potential you have though. Just looks like it needs some fine tuning to smooth it out. Unless perhaps there are just issues with the actual dyno run itself.
Or did they just not bother trying to dyno full throttle below 3-3500rpm ?
Hi Steve,As far as rpm's go. It's a RV8 with a very mild cam. So it isnt surprising it's dying off at the top end. That's just how they are. But depending on gearing, that might not be a problem. It certainly has the torque to make up for it.
It's unlikely it's down to the turbos seeing as a 2.0 turbo Impreza will happily rev to 7k+ making 300bhp at a push with one of those turbos.
The rover will never replicate that though.
The high torque output does show the potential you have though. Just looks like it needs some fine tuning to smooth it out. Unless perhaps there are just issues with the actual dyno run itself.
Or did they just not bother trying to dyno full throttle below 3-3500rpm ?
I remember hearing him say the actuators were weak they started to crack at 3psi, so we have put a bleed off pipe on the boost line to get me to 10psi. Would that have an effect?? In 5th only seems to go over 10psi to around 14psi
The cam I was going to get originally but was talked out of it was this one by V8 Tuner http://www.v8tuner.co.uk/product.php?id=483 would this be better suited than what I have??
These were the final runs after mapping sessions, he said his own v8 supercharged car did the same tailing off so who knows, he is on an original 3.9 rover v8 cam though.
Thanks
Neal
neal1980 said:
stevieturbo said:
TBH, that graph makes it look laggy. Makes it look like you dont have stable boost.
As far as rpm's go. It's a RV8 with a very mild cam. So it isnt surprising it's dying off at the top end. That's just how they are. But depending on gearing, that might not be a problem. It certainly has the torque to make up for it.
It's unlikely it's down to the turbos seeing as a 2.0 turbo Impreza will happily rev to 7k+ making 300bhp at a push with one of those turbos.
The rover will never replicate that though.
The high torque output does show the potential you have though. Just looks like it needs some fine tuning to smooth it out. Unless perhaps there are just issues with the actual dyno run itself.
Or did they just not bother trying to dyno full throttle below 3-3500rpm ?
Hi Steve,As far as rpm's go. It's a RV8 with a very mild cam. So it isnt surprising it's dying off at the top end. That's just how they are. But depending on gearing, that might not be a problem. It certainly has the torque to make up for it.
It's unlikely it's down to the turbos seeing as a 2.0 turbo Impreza will happily rev to 7k+ making 300bhp at a push with one of those turbos.
The rover will never replicate that though.
The high torque output does show the potential you have though. Just looks like it needs some fine tuning to smooth it out. Unless perhaps there are just issues with the actual dyno run itself.
Or did they just not bother trying to dyno full throttle below 3-3500rpm ?
I remember hearing him say the actuators were weak they started to crack at 3psi, so we have put a bleed off pipe on the boost line to get me to 10psi. Would that have an effect?? In 5th only seems to go over 10psi to around 14psi
The cam I was going to get originally but was talked out of it was this one by V8 Tuner http://www.v8tuner.co.uk/product.php?id=483 would this be better suited than what I have??
These were the final runs after mapping sessions, he said his own v8 supercharged car did the same tailing off so who knows, he is on an original 3.9 rover v8 cam though.
Thanks
Neal
well done mate 
couple of those turbo guys giving advice comes in handy too 
neal1980 said:
Hi Steve,
I remember hearing him say the actuators were weak they started to crack at 3psi, so we have put a bleed off pipe on the boost line to get me to 10psi. Would that have an effect?? In 5th only seems to go over 10psi to around 14psi
The cam I was going to get originally but was talked out of it was this one by V8 Tuner http://www.v8tuner.co.uk/product.php?id=483 would this be better suited than what I have??
These were the final runs after mapping sessions, he said his own v8 supercharged car did the same tailing off so who knows, he is on an original 3.9 rover v8 cam though.
Thanks
Neal
The actuators may be a little soft, but that shouldnt pose a problem. But again, without boost graphs it's impossible to say. On actuator only, what does the boost graph look like ?I remember hearing him say the actuators were weak they started to crack at 3psi, so we have put a bleed off pipe on the boost line to get me to 10psi. Would that have an effect?? In 5th only seems to go over 10psi to around 14psi
The cam I was going to get originally but was talked out of it was this one by V8 Tuner http://www.v8tuner.co.uk/product.php?id=483 would this be better suited than what I have??
These were the final runs after mapping sessions, he said his own v8 supercharged car did the same tailing off so who knows, he is on an original 3.9 rover v8 cam though.
Thanks
Neal
Surely the ecu can control boost ? This would give you full control and be much better than a simple bleed valve.
Again, mild cams are a safe bet, so I wouldnt say that it's a bad choice. But is is very mild. Rover V8's just arent revvy engines though. Even my own with a bigger cam never really liked going above 6000rpm. So it isnt too dissimilar to yours in that respect and mine had ported heads, triple springs, bigger cam and bigger turbine housings. So it wasnt a restriction aspect in that sense. So a bigger cam again may have helped it rev, but it would have been pointless really.
The torque is dropping off quickly above 4k because the heads can't breathe any more air at high rpm. Once the power has maxed out the torque MUST drop as the revs rise. Putting your engine spec at 10 psi into my power prediction program it's producing exactly what the computer says i.e. about 360 bhp so there's nothing more to come without more boost or big valve ported heads. They could add 100 bhp or so at the same boost level.
What doesn't look right is the turbos should be spooling up far quicker than they seem to be. Power at 3000 rpm should be about 270 bhp not the 200 it actually has so I doubt if it was showing more than about 5 psi boost there. If you can fix that you'll have a much nicer shaped torque curve.
What doesn't look right is the turbos should be spooling up far quicker than they seem to be. Power at 3000 rpm should be about 270 bhp not the 200 it actually has so I doubt if it was showing more than about 5 psi boost there. If you can fix that you'll have a much nicer shaped torque curve.
Pumaracing said:
The torque is dropping off quickly above 4k because the heads can't breathe any more air at high rpm. Once the power has maxed out the torque MUST drop as the revs rise. Putting your engine spec at 10 psi into my power prediction program it's producing exactly what the computer says i.e. about 360 bhp so there's nothing more to come without more boost or big valve ported heads. They could add 100 bhp or so at the same boost level.
What doesn't look right is the turbos should be spooling up far quicker than they seem to be. Power at 3000 rpm should be about 270 bhp not the 200 it actually has so I doubt if it was showing more than about 5 psi boost there. If you can fix that you'll have a much nicer shaped torque curve.
Im sure the standard 4.0 TVR heads are very poor they only have double valve springs I think no porting or bigger valves. So plenty room for improvment there I reckon What doesn't look right is the turbos should be spooling up far quicker than they seem to be. Power at 3000 rpm should be about 270 bhp not the 200 it actually has so I doubt if it was showing more than about 5 psi boost there. If you can fix that you'll have a much nicer shaped torque curve.
regarding the turbo spool they certainly seem quick any checks I can do on things there?? Once the turbo spin I can see on the boost gauge 10psi.
Many Thanks
Hi,
As my heads are the big restriction now completely standard 4.0 heads I am starting to explore different avenues.
I have been offered a set of Buick 300 alloy heads. These have the much bigger ports and valves and bigger combustion chambers which will hopefully allow me to lose my de-compression plates.
Does anyone have any experience with these, there from one year only I believe 1963 so will be checking them soon. Wants £400 for them which I didnt think was bad.
A good base to start from for big flow I believe.
As my heads are the big restriction now completely standard 4.0 heads I am starting to explore different avenues.
I have been offered a set of Buick 300 alloy heads. These have the much bigger ports and valves and bigger combustion chambers which will hopefully allow me to lose my de-compression plates.
Does anyone have any experience with these, there from one year only I believe 1963 so will be checking them soon. Wants £400 for them which I didnt think was bad.
A good base to start from for big flow I believe.
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