Looking for trim!

[theghosttanker]

I'm starting to gather up the parts for an L-28 turbo build to put in my 240. I've read stickies here until my eyes glaze over and I'm still confused.

I'm pretty sure that what I want is a T3/T4. I'm looking for something like 350 HP on a stock bottom end with the ability to get more(but not more than 400 HP) if I get forged pistons later on. I'll be megasquirting it.

The trim thing has me confused. I understand that trim is a ratio of inner/outer wheel diameters and I have seen T3/T4's for sale advertised with different trim numbers..eg .60 trim. I have also seen "P" trim or "S" trim advertised and discussed. Dunno what that means, either. My essential understanding is that different trim numbers affect the turbo lag and boost threshold, and that a lower trim number has a lower boost threshold and spools quicker but runs out of oomph at high rpm's. Am I right about this? I have no idea as to what range of trim numbers translate to what kind of performance.

I have driven two turbo cars...a WRX and a Jetta. I hate the way the WRX runs...it doesn't make full boost until about 4000rpms and the throttle response is slow. It loses boost between shifts and you have to wait for it to build again. My jetta starts boosting strong at 2000 RPM's and throttle response is much better, and it doesn't lag between shifts. (It does, however, seem to run out of breath past 5000 RPM's) I LOVE it; it's the car that has made me decide to try a turbo 240 after more than 20 years of hot-rodding Z's. But I will be really disappointed if it drives like the WRX and if I have to stop short of my ultimate horsepower goals in order to keep it driving like a Jetta then I will.

So is the T3/T4 the right turbo? Do I need to look for a certain trim? Are there more modern cartridge bearin turbos I should be looking at? And should I be avoiding the "new" T3/T4 turbo deals that I'm finding on E-Bay...they seem too good to be true.

I'm a thrifty penny pinching Scottish scrooge and I'm trying to keep this inexpensive, but my strategy for that is to take my time and wait for good deals, not to buy shoddy parts.Any advice?

[letitsnow]

t3/t4 is a VERY generic term, kinda like 'built' motor. It tells that it's not stock, but not much more.

 

There are 2 common compressor series used, T04b and T04e. The T04b compressors are generally identified by letters, such as S trim or V trim. They are older designs that don't act as nicely at high pressure ratios. T04e compressors are generally identified by numbers, ie. 50 trim or 57 trim. Compressor maps tell you everything about them.

 

Boost threshold(what's commonly called turbo lag) is determined by the exhaust side more than anything.

 

You should probably check out maximum boost by corky bell, it gives a much better description of everything and the math to back it up.

[theghosttanker]

Have looked and looked for a copy of maximum boost, it's out of print.

[Pyro]

avoid the T04B compressors (s, v1/v2, h2 trims). You need a T04E. However, the T04E will require a 1/2 inch spacer and therefore longer studs to work with the stock manifolds.

 

If you want low rpm boost then use a stock L28 T3 exhaust turbine (.63 a/r). If the turbine is modified for more flow, then it will rise the boost rpm.

 

A stock exhaust turbine works well with a stock cam. If you plan to install a bigger cam then modify the exhaust turbine flow to match the cam.

 

T3 turbine's have ratings or stage 1 to stage 5 (not sure of the a/r's at each stage). For example, a stage 3 will typically will not make full boost on a L28 until 3500 rpm and works well with a cam that pulls to 6500 rpms.

 

I would recommend a T04E-50 trim compressor. Seems to be a good fit for both low and high hp applications.

 

I would buy a used stock L28et turbo and have the compressor changed at a turbo shop. And they can also modify the turbine if a bigger cam is to be used.

[theghosttanker]

So I was nosing around on e-bay and saw this...

.http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=180310913186&sspagename=STRK%3AMEWAX%3AIT&viewitem=

is a turbonetics turbo a good brand? (I've been looking only at garrets). With the 40 trim would it work well on a mostly stock l-28? Please don't bid on my turbo!

[240zwannabe]

your jetta's turbo is tiny!!!!! if you want 350hp your going to have to be a little more patient at the pedal.

 

and maximum boost is still for sale...at the world's most famous online book seller at that. http://www.amazon.com/Maximum-Boost-Turbocharger-Engineering-Performance/dp/0837601606

 

search next time

[junglist]

avoid the T04B compressors (s, v1/v2, h2 trims). You need a T04E. However, the T04E will require a 1/2 inch spacer and therefore longer studs to work with the stock manifolds.

 

Any justification as to why you say this? What is so bad about the T04B compressors that you should avoid them in favor of a T04E?

[Pyro]

T04B is an old compressor design made for diesels. The s and v1/v2 trims are not much better than the stock T3, so not worth the upgrade. The H3 has a lot of hp potential but is on the verge of surge if boost comes on before 3500 rpm.

 

I run a H3 myself because I got lazy and did't want to use a turbine spacer that the t04e requires. but my cam and turbine are big enough to delay boost until 3500 so it works for me (barely). However, my long term plan is to re-do with a t04e-50.

 

check out this compressor site, then you will see what I mean. the to4e-50 is a really good compressor for the L28. http://www.squirrelpf.com/turbocalc/

[Pyro]

get this turbo, but without the kit.

 

http://cgi.ebay.com/ebaymotors/_Car-Truck-Parts-Accessories__Turbo-Kit-Honda-Civic-D-D15-D16-92-00-T04E-50-TRIM_W0QQitemZ400017893623QQadiZ2865QQadnZCarQ20Q26Q20TruckQ20PartsQ20Q26Q20AccessoriesQQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item400017893623&_trksid=p4506.c0.m245&_trkparms=72%3A543%7C65%3A12%7C39%3A1%7C240%3A1318#ht_3018wt_1713

[letitsnow]

T04B is an old compressor design made for diesels. The s and v1/v2 trims are not much better than the stock T3, so not worth the upgrade. The H3 has a lot of hp potential but is on the verge of surge if boost comes on before 3500 rpm.

 

I run a H3 myself because I got lazy and did't want to use a turbine spacer that the t04e requires. but my cam and turbine are big enough to delay boost until 3500 so it works for me (barely). However, my long term plan is to re-do with a t04e-50.

 

check out this compressor site, then you will see what I mean. the to4e-50 is a really good compressor for the L28. http://www.squirrelpf.com/turbocalc/

 

I'd have to disagree, the v1/v2 flows 56lb/min. The s is kinda small, but still an upgrade from a t3. I wouldn't go and seek out a t04b compressor, but if you get a good deal like I did($50 for the turbo) I wouldn't turn it down.