I think that everything came out right while doing this, and I am excited by the results.

Using the formulas found in the thread about reading compressor maps and the compressor map for my v-trim TO4B http://64.225.76.178/catalog/compmaps/fig7.html I figure that my car will run these numbers. First equation is at optimum turbo flow, second is at redline.

2.6L x 5000rpm x 90%VE x 2.0PR / 5660 = 413.43 CFM = 28.97 lb/min

28.97 lb/min x 7.69 = 222.78whp


2.6L x 7000rpm x 90%VE x 2.0PR / 5660 = 578.80 CFM = 40.56 lb/min

40.56 lb/min x 7.69 = 312whp

Now that is considering stock ports. As above link states, add 15% for a ported engine and you get 256.2 whp at optimum flow and 358.8 whp at redline.

I am pretty sure that i did this right, but if anyone finds a mistake please post up about it.

 

this is @15lbs of boost. Up it to 20 lbs with ported block and I get 430 whp at redline.

 

your math is pretty close, but slightly on the high side.

with this turbo i made 360whp@15psi on my s5 TII with a small streetport (and stock exhaust ports) this was at 15* advance and a 12* split. my turbo specs were: t04b v1/v2, 1.15 a/r tangential turbine p-trim wheel

that turbo will run out of steam above 16-17psi.

 

Yeah, i have read many threads that say the v trim wheel optimizes at 15 psi, but if you look at the comp map it "could" be working at up to 65% efficency at 20 psi (approx 2.4 PR).

 

Yeah, i have read many threads that say the v trim wheel optimizes at 15 psi, but if you look at the comp map it "could" be working at up to 65% efficency at 20 psi (approx 2.4 PR).

by the way, how does your 1.15 hotside spool on a street port? I have the same hotside A/R and I have read that it is usable, but a bit laggy.

 

sorry, doulble post, and the full specs on my turbo are TO4B V trim comp, 1.15 ar hotside p trim.

 

the 1.15 a/r was much too laggy. in 4th gear, full boost (15psi) didnt happen until about 5000rpms. it made great topend power though.
i'd recommend getting a .81 collected or .84 divided p-trim turbine housing. power wouldnt suffer much, and the response would be much better.

 

how much of a difference would a divided housing and fully divided manifold make on lag? with a medium streetport of course.

 

I use a different method, but your final numbers look pretty good as far as I can tell. Your results will be a little on the high side because you assumed 100% thermal efficiency, which admittedly is difficult to determine because of all the variables. However, I think it is good to err on the high side so that you will end up choosing your fuel system and driveline components on the safe side. Just realize that 100% efficiency is not possible without supercooling, so your actual numbers will be lower, and there is no reason to be upset when this happens.

Also, keep in mind that the pressure ratio on the compressor map is measured at the compressor discharge. You will likely take your boost readings off the intake manifold, which will have somewhere around 2psi drop due to the intercooler and plumbing losses. Therefore, 15 psi boost on your boost gauge will cause the turbo to run a pressure ratio of about 2.16 on a standard day rather than 2.02.

 

I just built a vehicle with that same setup, 15psi by 3200rpms according to the dyno... Man what are you running a 2.5" exhaust with a cat???

 

meh, I don't trust those calculators.

think of it this way--If I want to appraise my house, do I come up with a complicated economic model to predict its selling price? Or do I just look and see what the other houses in my neighborhood went for?

 

no, I am not running a cat. And just to clear this up, what does that have to do with anything we are talking about?

I am not a complete noob. Obviously I know that I should run a larger exhaust with this turbo. This thread has absolutely nothing to do with how my car is currently setup. I am still in the planning stages, and I did this so I could have a mathmatcal idea of what the turbo is capable of (under PERFECT condidtions, which will never happen), that way I know how to plan the supporting mods accordingly.

I don't want to go into this build making mods that will be overkill and make my wallet cry.

 

That's really the best way to do it for those who build a lot of cars, especially when it comes to choosing a turbine A/R ratio. Unfortunately, random hearsay doesn't work so great for a novice because people lie, are mistaken, and/or accidentally leave out certain details. It's probably best to use both methods to come up with a good SWAG. One of my friends says that no matter how much you plan, you will still end up screwing up something, which I have found to be true. If you think about it, if it were possible to plan perfectly, there would be no such thing as test pilots.

 

Not going to happen. If you want lots of HP, you need lots of $$. Do it right the first time. CJ

 

yeah i just realized that i worded that wrong. i meant that i didn't want to spend money on parts that would just be overkill.

 

Actually, overkill is not necessarily a bad thing when talking about turbo systems...

I agree that you can calculate yourself to death and still not get an agreed upon value.
What does work in the real world is...what people have done in the past.
The T04B V-trim is proven to put down 300hp at the wheels (DynoJet) no problem on pump gas - under 18psi.

Pushing more boost than that is not recommended on pump gas.
If you want more power, why not go with a bigger turbo and turn the boost down?

The T04B H-trim is the next compressor size up, and it has been proven to put down 350 at the wheels.


-Ted

 

I am not really worried about how much power I put out, as long as it is more than I have now. I already have the TO4B (got it for free) so I will just run it. If I can get 300 whp I would be more than happy.

 

This is dyno from customer. Turbo sold is T04b V trim with 1.15 P trim turbine.
Engine is 13b stage 2.

354 @ 14psi, but peek power was actually made at 12psi during peek revs. The boost drop shows the compressor is reaching flow limits on 13b after 5000rpm at boost levels 14psi or falling of the map at this pressure vs cfm?

As RETed said don’t get caught up in the math behind compressor maps, Maps are best used as comparisons between other compressors, There not an easy tool to read in terms calculating how much power you will make at a certain boost level, There’s just to many other parameters like cfm changes with engine revs even if boost is constant this will result in a compressor efficiency changing as engine rpm increases.

 

15psi by 3200rpms in 4th gear with a T4 p-trim 1.15 turbine A/R?

in case i didnt mention it, i had stock exhaust ports. and a full 3" exhaust

i admit, i did have a small exhaust leak pre-turbo (at the wastegate), but in 4th gear i could never hit 15psi before 4500 rpms.



my numbers seem to be on par with the others though, as i made 360whp/305wtq on a dynojet.


and Ted, only 300whp @18psi? maybe you've mistaken the t04b v1/v2 for a T28? several of us have dyno'd over 350whp with this turbo at or under 15psi.

 

I estimate on the low side.


-Ted

 

i'd say.

low by about 50whp and at 3psi more boost!

that's a decent turbo.

 

Exhaust ports aren't stock, and its got a 3.5" exhaust, no puny 3" stuff here =P

 

i was young and naive back in my TII days, sir. you seem to be totally badass, and for that i applaud you.

 

lol jackass. You know I only ride you're posts because you called me crazy for running big turbine housings saying they were too laggy...

 

haha i was just messing with you, guy.

love always,

Mr. Cartmill