cool
any comments on the current driving experience without the front w d.

 

Nice one!

 

Ed please exlain for me what the 8.9 to 1 CR is??
How does this effect drivability?
How is it adjusted?
Thanks, many of us are trying to understand this complex "sport"
I cannot wait to hear your first encounter with a new Z06 or the new
Viper!!! (Make sure you get some traction).
Marty K

 

Marty,
that is the Compression ratio, it is higher, meaning it will give you better drivability at the low end of the powerband and more torque than the regular TT. The downside to that is th etop end since you cannot increase boost as much as you would a stock CR engine, therefore your top end perfromance will suffer somewhat vs. a higher boost, lower compression engine. For a city driven TT and the occasional backroads, higher compression is a lot of fun. You can do that in several ways, P&C, Heads, crankshaft, etc..Not sure on the TT enignes, which is best.
The Z06 and Viper are no match for this car in acceleration IMO.

 

Keep in mind that the extra mechanical compression may have been bled off by the longer duration cams resulting in the same corrected compression as a stock car.

Compression ratios are expressed in two way. One is static and the other is corrected.

Static compression is what we normally see. 8.5 to 1 for example. That means that there are 8.5 parts of air (from BDC) being forced into the chamber at TDC. This is a mechanical value does not take into consideration the valve timing.

Corrected compression takes into account the closing of the intake valve. After the piston reaches BDC and is on its way up (during intake cycle) the intake valve remains open. How long it remains open depends on the cams being used. Typically the hotter the cam the longer the intake valve stays open after BDC. This results in lower corrected compression. You can recover this lower compression by adding back static compression.

Adding back lost compression will help offset normally lost bottom end power.

Since I don't have the cam timing for each one I can't say if Todd just added back lost CR or went beyond that. One thing is for sure is this 3.8 protomotive motor has the best power band I have ever seen on an air cooled 2v motor. Not insulting you guys with greater HP I am only commenting on the shape of the curve.

 

Holy cow!,dats awesome, love the Protomotive setups.

 

Thanks all! If anybody's headin' east with a place on their car carrier in next week or two let me know!!

Prison rules Vince?! If you'd take that spoiler off you'd gain at least 30 HP :-)

Feel free to ask away... I have been using Todd's 'stuff' and stealing freebies for 15 years :-)... built the first two bastardizations.. David and Todd did my last two...

K24 .. good points but Todd is very careful with cams and actually has some ground for him when necessary to address the timing/overlap/lift issues you mention... in general he tends to play in teh .440-490 lift on both sides and 220-290 degrees duration. .. these are gt2 EVO grind.. forgot specs... but in general (for group FYI).. in turbos/blowers you want the highest practical lift coupled with a modest duration/overlap that will keep the charge in the cylinder in practical terms.(rememeber there is pressure forcing the charge into the cylinder, so if an exhaust valve is open at a 'marginal' time the air/fuel chjarge will blow right out.... kinda what k24 is addressing in his compression views.. (yes?)

In NA engines the inlet and exhaust pulsings are major factors in flow and these are not necessarily hurt by extreme overlap since they tend to improve flow into the cylinders.. but turbo engines really don;t care about those isses under boost...

Thanks, Ed

 

Perfect, then we know you don't belong to the tire spinning idiots and prefers the good traction.

I'm though concerned that Ed will not be able to put 315 on his sleeper since it wouldn't fit. Or would it?!!

 

Rassel,
Admit that it can be fun sometimes
Viperbob had 315s in the rear if I recall correctly with stock fenders. Might have to roll the fenders though. The issue is the rim width and fitting those sizes on them. On a car like Ed's, traction is certainly one of his biggest concerns.

 

Poor him...

 

edpurplett,

Yes it is the duration of the intake valve namly the intake valve closing that affects the corrected compression ratio.

You are correct that you want most of the flow increases from lift. There is a formula for lift that is determined by valve sizes. Past a certain point you get no gain.

Overlap on a turbo motor is very different than a NA motor. You do however increase it in smaller increaments than a NA motor. This is why sizing the hot side of the turbo is so important. That quick response from small hot side turbos (k16's) will have high Turbine inlet pressures forcing the exhaust gases backworks during overlap. Larger turbos like your T3 Super 60's do not suffer the same fate.

Todd understands all of this very very well. You will never see him use a small K16 based turbo.

You chose your tuner well. He will be doing some head/cam work for me when the time comes.

FWIW guess who helped me on my software and hybrid K24's???

 

k24... Very Cool! Todd doesn't get enough credit because he is so Damn modest... have you been for a ride in my ride ;-)... since you knew it had Super 60's and I never mentioned it ;-)... it is even faster.. he recal'd it two weeks ago.... woowheee and the engine MIGHT be broken in..

Or you know that is one of his favs.. also what I have on my current ride...

 

Ed,
You did mention it had Super 60's. Although I can understand that in your excitement you don't know what you said
Are you sleeping at night?

 

Jean,...I haven't slept well in three weeks... also because I haven't actually driven it :-0... I trust Todd implicitly... but I'm not sure it will actually be faster than my current rig.. only more tractable..... and I think in reality I will actually need to stopwatch it to know for sure since the difference in ratios is insane... third in this car is exactly what my second gear does now....in mph.. we will see.. and for backroads it will be much better... current rig 1st is too short for anything even though it gors to 45.. and 2nd (when it spools) can be too fast for tight stuff... and the torque delivery isn't linear like the new 3.8... I'll shut up... just anxious... also never had me an engine quite this expensive.. I'll be wincing first three or four times on boost ;-)

 

Edpurplett,

No I have not been for a ride in your setup. You did mention in an earlier post that you have super 60 turbos. I am running the same super 60 compressor that you are. It is really well sized for the 3.6-3.8 ltr motor. Mine are K24 based while yours are the T3's.

If I had some more cash I would have done it the exact same way that you have!

Todd is a humble man. He does not need to troll internet forums telling everybody how great he is. His workmanship produces real power time and time again.