Con rod specs for Turbo Technics TT
Discussion
stevieturbo said:
But is it a very old gas ring type, or is it a modern electronic injection type ?
In order to work, he'd need full control over gas injected, not just what most do and try and rely on a narrowband lambda sensor at idle, and adjust some fuel trims based on that.
That primitive approach often ends up with blown engines.
Thanks, it's a modern Italian controller, but if it does not suffice, no worries, the guy knows his stuff and if he needs to change it he will.In order to work, he'd need full control over gas injected, not just what most do and try and rely on a narrowband lambda sensor at idle, and adjust some fuel trims based on that.
That primitive approach often ends up with blown engines.
Last question, will the exhaust need any modification. Currently it's a SS straight through.
226bhp said:
3" is a good size for that, after where the two pipes join which should be around 2.25" each. You can go smaller, it will just be a touch restrictive that's all, no big deal.
Single 3" would easily support 600hp, and then some.A pair of 2.25" has a larger CSA than a single 3", so again would easily support that sort of power level with no restriction worth worrying about.
Although all the above assumes sensible routing without lots of crazy bends and straight through boxes.
stevieturbo said:
Single 3" would easily support 600hp, and then some.
Not according to my chart.https://web.archive.org/web/20110903091024/http://...
Pumaracing said:
Have made close to 750hp with a 3" system and less than 2psi restriction measured close to the start of the system, about 18" from the turbo.And that's a very quiet 3" system with two large silencers.
Your chart may show optimal, or perhaps with no restriction whatsoever.
But that isnt to say much higher power can be produced with only a quite insignificant restriction.
stevieturbo said:
Have made close to 750hp with a 3" system and less than 2psi restriction measured close to the start of the system, about 18" from the turbo.
Hmmm, interesting. I have enough data to know the chart is correct for N/A engines but have been rethinking now whether it does also apply to turbo ones and suspect that perhaps this is more complex and depends on the boost level and hence the amount of energy extracted from the exhaust gas stream.Pumaracing said:
Hmmm, interesting. I have enough data to know the chart is correct for N/A engines but have been rethinking now whether it does also apply to turbo ones and suspect that perhaps this is more complex and depends on the boost level and hence the amount of energy extracted from the exhaust gas stream.
I'm sure any restriction can be seen as a negative....but how much that will actually affect performance is another matter.A few years back I had a pair of spiral flow silencers in the middle of my car. Pretty crap really.
Basically an old spiral staircase type design. Central hole, maybe 35-38mm diameter and the rest of the silencer made up from the spiral.
2 x 3" system, making enough power to hit 198mph over a standing 7/8th mile ( rabbits apparently ate through their cables so they had to shorten the distance...WTF )
Not too bad really....until I realised some time after the silencers had totally collapsed and there was barely a hole 40mm diameter on each pipe for the exhaust to breathe through.
Now in this instance, I was seeing around 12psi in the collector at close to 7000rpm, but never really though much of it. That's my V8, supercharged, so n/a on the exhaust side of things.
Really..I couldnt feel any difference than when the silencers were new !! LOL Which is kinda shocking.
In terms of exhaust back pressure effects on power, the following rules apply (as a guide)
1) The reduction in BMEP is a direct 1:1 relationship with EBP (due to pumping losses) so 10kPa more EBP is 10kPa less BMEP.
2) The reduction in airflow (and hence fuel, and hence power) due to a poorer pressure ratio across the engine (inlet pressure / exhaust pressure), generally between 1 and 3 bhp per kPa for a typical road car engine
3) The reduction in spark efficiency due to a higher exhaust gas residual content in the cylinders (reduced pressure ratio and increased reverse flow across the exhaust valves and high pressure in the crevice volumes at EVC) This is highly dependant on the dynamic compression ratio and the chamber burn characteristic, but for highly boosted (and hence knock limited) engines this can be as high as 5bhp/kPa, down to less than 0bhp/kPa for a low compression N/A engine running at MBT.
As a ball park, a typical "road tune" 175bhp 2litre N/A engine will have an total EBP sensitivity of around 3 to 5 bhp/kPa, and a boosted 2 litre turbo (say >275bhp) will sit at around 5bhp/kPa. Generally, the higher the specific output of the engine, the more sensitive it will be, with for example a typical WRC (inlet restricted) engine sitting around 12bhp/kPa !!
1) The reduction in BMEP is a direct 1:1 relationship with EBP (due to pumping losses) so 10kPa more EBP is 10kPa less BMEP.
2) The reduction in airflow (and hence fuel, and hence power) due to a poorer pressure ratio across the engine (inlet pressure / exhaust pressure), generally between 1 and 3 bhp per kPa for a typical road car engine
3) The reduction in spark efficiency due to a higher exhaust gas residual content in the cylinders (reduced pressure ratio and increased reverse flow across the exhaust valves and high pressure in the crevice volumes at EVC) This is highly dependant on the dynamic compression ratio and the chamber burn characteristic, but for highly boosted (and hence knock limited) engines this can be as high as 5bhp/kPa, down to less than 0bhp/kPa for a low compression N/A engine running at MBT.
As a ball park, a typical "road tune" 175bhp 2litre N/A engine will have an total EBP sensitivity of around 3 to 5 bhp/kPa, and a boosted 2 litre turbo (say >275bhp) will sit at around 5bhp/kPa. Generally, the higher the specific output of the engine, the more sensitive it will be, with for example a typical WRC (inlet restricted) engine sitting around 12bhp/kPa !!
Max_Torque said:
As a ball park, a typical "road tune" 175bhp 2litre N/A engine will have an total EBP sensitivity of around 3 to 5 bhp/kPa, and a boosted 2 litre turbo (say >275bhp) will sit at around 5bhp/kPa. Generally, the higher the specific output of the engine, the more sensitive it will be, with for example a typical WRC (inlet restricted) engine sitting around 12bhp/kPa !!
Bolllocks! Yer talking oot yer arse loon. 1 kPa is only 0.145 psi. Yer saying a 175 bhp N/A road engine with only 2 psi back pressure would lose between 41 and 69 bhp. Ye daft southern numpty. Git back under yer bloody bridge. 
Pumaracing said:
Max_Torque said:
As a ball park, a typical "road tune" 175bhp 2litre N/A engine will have an total EBP sensitivity of around 3 to 5 bhp/kPa, and a boosted 2 litre turbo (say >275bhp) will sit at around 5bhp/kPa. Generally, the higher the specific output of the engine, the more sensitive it will be, with for example a typical WRC (inlet restricted) engine sitting around 12bhp/kPa !!
Bolllocks! Yer talking oot yer arse loon. 1 kPa is only 0.145 psi. Yer saying a 175 bhp N/A road engine with only 2 psi back pressure would lose between 41 and 69 bhp. Ye daft southern numpty. Git back under yer bloody bridge. Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff