Want another second in the 1/4 mile

[KevinBuckham]

Because without a ball bearing centre section your car will accelerate like a bag of dicks, unless you want to drag race ALL THE TIME.

*Edited to remove flaming comments.*

There was a fascinating comparison of turbo spool (lower RPMS until 15 PSI boost) and lag tests (higher RPMS until 15 PSI of boost) and the results are NOT what the "tooner" forums suggest at all.  

For example, both the TD06 20G and a PTE "50 trim" had better spool profiles than either a GT12 OR a FP3052!  The EVO 16G outspooled the other larger turbos including the 20G by a very large margin.  Fascinating stuff.

The "50 trim" (FP Green et al.) was very similar to a 20G, and is much more efficient up top.  The "60-1" trim has lousy spool characteristics, but could help Aaron hit low 11s very easily for half the cost of many ball bearing turbos.

Oh - and what Robin said.

[KevinBuckham]

Or, if you want to save your money, keep your evo 16G...

He has a regular (non EVO) 16G.  Good turbo, but the compressor is far less efficient in the higher flow and boost maps.  It is still possible to get a non EVO 16G into the 11s, but probably not at stock weight w/o nitrous.  

I believe that Aaron doesn't want to drive a "tin can", but perhaps we can get him to change his mind.  :twisted:  :wink:

[Martin Raska]

There was a fascinating comparison of turbo spool (lower RPMS until 15 PSI boost) and lag tests (higher RPMS until 15 PSI of boost) and the results are NOT what the "tooner" forums suggest at all.  

For example, both the TD06 20G and a PTE "50 trim" had better spool profiles than either a GT12 OR a FP3052!  The EVO 16G outspooled the other larger turbos including the 20G by a very large margin.  Fascinating stuff.

The "50 trim" (FP Green et al.) was very similar to a 20G, and is much more efficient up top.  The "60-1" trim has lousy spool characteristics, but could help Aaron hit low 11s very easily for half the cost of many ball bearing turbos.

That's boost threshold, which is very dependant on other properties.  If you compared the actual lag time, say during shifting gears, the results would probably be different.  I have seen tests that I think were done well that show turbo lag characteristics on shifts to have BB center cartridges reach full boost close to 3 times faster in some instances when matched against a relating sleeve bearing cartridge, supressing as many variables as reasonably possible.

[Robin Toor]

Does BB spool up faster? Yes.

Is it worth the extra $1000 to buy a BB turbo for straight line racing? No.

In events like autox, yes it does help to buy a BB turbo, since you are constantly off and on the turbo, dropping in and out of boost, it does help to get back into boost ASAP before the next corner. However, in straight line racing, yes the BB will spool a bit faster, but thanks to things like anti-lag and keeping the revs up, you pretty much are in constant boost the whole time down the track. You are able to leave the line in boost, and keep the car in boost as long as you keep the revs up beyond the rpm in which you make max boost (for me this is 5000rpm @ 22psi).

Yes BB does spool up faster, but it is not as great as everyone makes it seem and does not help you that much in straight line racing. In Aaron's case, he wants to go fast in a straight line, and $1000 is better spent elsewhere than on a BB cartridge.

[Aaron dusseault]

I just wanted to let you guys know I realy apreciate your input. I value your oppinions and just want to make a good choice. I am starting to sway toward a 20g with an upgrade to 660 injectors and a matched chip for my vpc. Do you guys feel I should spend the dough and go external wastegate? If so any recomendations? and can I just weld a flange on my exhaust manifold? Any thoughts on porting or clipping the 20g Or do you think clipping it will create to much lag as I do spend a lot of time just cruising the roads on the island.

[Andrew Scott]

All I'm trying to say is that if you're going to be driving your car anywhere besides the dragstrip (lets say work, 7-11, gas stations), and you don't want it to feel like a bag of shit before 4800 rpm, your best off with a BB turbo.

[Robin Toor]

I just wanted to let you guys know I realy apreciate your input. I value your oppinions and just want to make a good choice. I am starting to sway toward a 20g with an upgrade to 660 injectors and a matched chip for my vpc. Do you guys feel I should spend the dough and go external wastegate? If so any recomendations? and can I just weld a flange on my exhaust manifold? Any thoughts on porting or clipping the 20g Or do you think clipping it will create to much lag as I do spend a lot of time just cruising the roads on the island.

I think you should go external wastegate, just to save yourself from the headache of possible boost creap and blown motors as a result of internal gates (It has happened to some people running 20G turbos). You can weld a flange for an external wastegate onto your existing manifold, or I can sell you a 2g exhaust manifold with a tial flange welded on it which you can install, then all you have to buy is the wastegate. I would port the 20G, but I wouldn't bother clipping it, since it already flows a lot of air and you don't really want more lag.

[Miles Frederick]

If you're getting a 20G with a td05h turbine side, then clipping can be beneficial at higher boost levels.  And always port it.

On the other hand as Robin mentioned if it is a td06 turbine side the default configuration should suffice.

The td05h will probably give you a little better spool (from what I've read a healthy setup should spool by around 3800), whereas the td06 will give you more top end with a slower spool.

From reading the various forums I've come to the conclusion that although a large flapper internal gate along with porting is enough for some, many seem to have trouble with creep.  Which is why I decided on an external setup.

I'm actually just in the process of installing mine (upgrading from a 16g as well although a small one), so I will let you know how it works out.  It's a td05h turbine side, clipped 15 degrees and ported fairly heavily, with a 38mm tial wategate manifold mounted.

[Aaron dusseault]

Guys I notice that you can mount an external wastegate to the manifold or I see some mounted to the o2 housing whats preferred and why? and what one do you recomend for a guy running 660s and a 20 g

[Mike Schmid]

Here's something fun.  

A really good lift to shift time in a synchro'd manual tranny is 0.3 seconds.

3 gear changes x 0.3 seconds = 0.9 seconds almost a full second!  

0.9 seconds of off throttle DEcellerating during a 1/4 mile run.  

How long does a turbo take to respool and make power again after a shift?  If one turbo happens to take 0.33 seconds longer to respool after a shift than another it will cost you a full second in the 1/4 mile all else being equal.  Now generally the bigger turbo will make more power and it'll make up for some of that loss but still, it's something to keep in mind.  

You can minimize some of that with NLTS/antilag and get the turbo back on boost faster.  But keep in mind NLTS is hard on the tranny and a better spooling turbo with the same NLTS will still spool that much faster than a laggier turbo.  

Don't tell me turbo lag isn't a factor in 1/4 mile times.  

[Miles Frederick]

From my understanding, the best position would be off the manifold at the collector.  Unfortunately with our cast manifolds this is not easy.  O2 Housing mounted is second as it still can vent all 4 exhaust pulses evenly, but still requires heavy porting of the wastegate hole in the turbine housing to work well.  Third is manifold off one of the runners, usually the #1 and can be mounted fairly close to the collector, it will not vent the exhaust pulses 100% evenly, but is usually the cheapest and easiest way.  From what I've read though, the differences in real world performance seem to be minimal

[Kimyee Lai]

If one turbo happens to take 0.33 seconds longer to respool after a shift than another it will cost you a full second in the 1/4 mile all else being equal.

It should be qualified that it'll cost a second of relatively less acceleration, not ET .

[Mike Schmid]

If one turbo happens to take 0.33 seconds longer to respool after a shift than another it will cost you a full second in the 1/4 mile all else being equal.

It should be qualified that it'll cost a second of relatively less acceleration, not ET .

Good call, I overlooked that.  During that time you will still be covering distance while you coast.  However it's still a full second you are not accelerating.

[Martin Raska]

Anti-lag can correct that drag racing spool shift problem pretty well.  If you're trying to figure out where to spend your money for a specific goal.

[Artem Goloubov]

I see some mounted to the o2 housing whats preferred and why? and what one do you recomend for a guy running 660s and a 20 g

Got a picture?