Trumpet length
Discussion
I'll save you a lot of hassle.
Basically the standard TVR airbox and trumpet lengths are pretty much spot on. Many people (TVR specialists included) have experimented with different trumpet lengths, and the repeat conclusion is that there's no meaningful gains to be had over the standard design.
Basically the standard TVR airbox and trumpet lengths are pretty much spot on. Many people (TVR specialists included) have experimented with different trumpet lengths, and the repeat conclusion is that there's no meaningful gains to be had over the standard design.
Hi Dave thanks for the reply. As you know I don't have an air box or trumpets, I'll dyno as is, then do something different.
What is the current trumpet length?
Is the act better?
How did they get an extra 40 hp for the s?
What was the gt spec/power output?
Is there any engine data out there as I was asked by a few why the output isn't higher given the spec? If I get chance I might run some simulations.
I have a spare head and will build that to a new spec, I may also have access to new rods/crank and pistons?
What is the current trumpet length?
Is the act better?
How did they get an extra 40 hp for the s?
What was the gt spec/power output?
Is there any engine data out there as I was asked by a few why the output isn't higher given the spec? If I get chance I might run some simulations.
I have a spare head and will build that to a new spec, I may also have access to new rods/crank and pistons?
I would seriously question the validity of the info on those old reviews you've found 
In reality the factory 'S' spec engines only ever pushed out 380bhp. The 405bhp claims from later cars is simply untrue.
The extra power (20 or so bhp) on the S spec engines was from different cams, bigger injectors, a larger bore exhaust system and a different ECU map. All factory Speed 6's used the same MBE ECU and it runs batch rather than sequential injection. Everything else is the same as a standard 4.0 ltr.
From a little research I've done, the GT/LeMans spec engines were basically blueprinted and stroked 4.2 ltr Speed 6's with top quality internals and racing cams. They also had subtle water jacket and lubrication system changes in the block which were carried over to later factory speed 6 engines. Further to this they had extra fuel injectors in a properly sealed airbox to prevent the mixture leaning out at higher rpm which is still a problem on factory cars. Not sure what ECU they used but suspect it ran sequential injection as it was TVR's intention to go sequential with later cars.
With the LM air restrictors in place they pushed out 440 bhp but the engines were totally unsuitable for road use.
In reality the factory 'S' spec engines only ever pushed out 380bhp. The 405bhp claims from later cars is simply untrue.
The extra power (20 or so bhp) on the S spec engines was from different cams, bigger injectors, a larger bore exhaust system and a different ECU map. All factory Speed 6's used the same MBE ECU and it runs batch rather than sequential injection. Everything else is the same as a standard 4.0 ltr.
From a little research I've done, the GT/LeMans spec engines were basically blueprinted and stroked 4.2 ltr Speed 6's with top quality internals and racing cams. They also had subtle water jacket and lubrication system changes in the block which were carried over to later factory speed 6 engines. Further to this they had extra fuel injectors in a properly sealed airbox to prevent the mixture leaning out at higher rpm which is still a problem on factory cars. Not sure what ECU they used but suspect it ran sequential injection as it was TVR's intention to go sequential with later cars.
With the LM air restrictors in place they pushed out 440 bhp but the engines were totally unsuitable for road use.
I'm not aware of any CR differences between the S and non S. They all use the same block, head, crank, rods and pistons so not sure how there could be????
Regards the trumpets, not sure of the actual length but the only people making new trumpets/airboxes are ACT with their carbon ones. Apart from looking very nice and being better made than the originals, I don't think that they give any meaningful power gains, maybe just shift the torque curve around a bit? As said the original TVR one is pretty much spot on.
You might be able to find one at a breakers yard and tart it up with some vinyl wrap, but they're still not cheap.
Regards the trumpets, not sure of the actual length but the only people making new trumpets/airboxes are ACT with their carbon ones. Apart from looking very nice and being better made than the originals, I don't think that they give any meaningful power gains, maybe just shift the torque curve around a bit? As said the original TVR one is pretty much spot on.
You might be able to find one at a breakers yard and tart it up with some vinyl wrap, but they're still not cheap.
dvs_dave said:
I would seriously question the validity of the info on those old reviews you've found
In reality the factory 'S' spec engines only ever pushed out 380bhp. The 405bhp claims from later cars is simply untrue.
The extra power (20 or so bhp) on the S spec engines was from different cams, bigger injectors, a larger bore exhaust system and a different ECU map. All factory Speed 6's used the same MBE ECU and it runs batch rather than sequential injection. Everything else is the same as a standard 4.0 ltr.
From a little research I've done, the GT/LeMans spec engines were basically blueprinted and stroked 4.2 ltr Speed 6's with top quality internals and racing cams. They also had subtle water jacket and lubrication system changes in the block which were carried over to later factory speed 6 engines. Further to this they had extra fuel injectors in a properly sealed airbox to prevent the mixture leaning out at higher rpm which is still a problem on factory cars. Not sure what ECU they used but suspect it ran sequential injection as it was TVR's intention to go sequential with later cars.
With the LM air restrictors in place they pushed out 440 bhp but the engines were totally unsuitable for road use.
All correct except I understand the S/red Rose engines had the same camshafts but had advanced cam timing. Also some early red rose engines had steel cranks and double valve springs.In reality the factory 'S' spec engines only ever pushed out 380bhp. The 405bhp claims from later cars is simply untrue.
The extra power (20 or so bhp) on the S spec engines was from different cams, bigger injectors, a larger bore exhaust system and a different ECU map. All factory Speed 6's used the same MBE ECU and it runs batch rather than sequential injection. Everything else is the same as a standard 4.0 ltr.
From a little research I've done, the GT/LeMans spec engines were basically blueprinted and stroked 4.2 ltr Speed 6's with top quality internals and racing cams. They also had subtle water jacket and lubrication system changes in the block which were carried over to later factory speed 6 engines. Further to this they had extra fuel injectors in a properly sealed airbox to prevent the mixture leaning out at higher rpm which is still a problem on factory cars. Not sure what ECU they used but suspect it ran sequential injection as it was TVR's intention to go sequential with later cars.
With the LM air restrictors in place they pushed out 440 bhp but the engines were totally unsuitable for road use.
When my engine was rebuilt in May 2006 at the factory, I swapped a few emails with the engine builder and when asking the difference between the S/RR/Sag engine this was part of his response.
"std 4.0 has a 1mm dish in the piston crown."
So, I assume that implies the RR/S/Sag engine does not have a dish in the piston.
"std 4.0 has a 1mm dish in the piston crown."
So, I assume that implies the RR/S/Sag engine does not have a dish in the piston.
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