Turbo question

[Sleepervr-4]

I am in the works of turboing my g and I am useing a T-25. I have already flipped the compressor outlet elbo for a fmic setup. Just wanted to know why you guys say it isn't a good turbo for the swap? Are 450cc injectors and a stock 2g turbo fuel pump ok? Also from pics I see all of you turbo buys are using internally gated turbos so you guys must not have problems with boost spike or creep? Where do you guys tap in for the turbo water lines?

Here is a list of parts going in. Let me know if anything is missing.

T-25
2g mani
2g O2 housing
450cc w/ resistor pack
2g fuel pump
1g bov
2.5 gst turbo back
boost, egt and a/f guages
triple a pillar pod
safc or 2nd gen mas translator
bar and plate fmic 22x5.5x2.5

and have a pocketlogger

[Proto]

a t25 is the WORST turbo out there. good luck with it!

[seth98esT]

Well its by far not the WORST turbo out there, but it is way undersized for a 2.4L motor.

[Sleepervr-4]

a t25 is the WORST turbo out there. good luck with it!

You never said why it is the worst. Is it because on a 2.4 I'll have full boost at like 2k? I had the turbo from my old 2g just sittin there so said why not put it to use. At 8 psi do you really need a 50 trim? You wont even be in its range.

Well its by far not the WORST turbo out there, but it is way undersized for a 2.4L motor.

Ok so what size turbo is best for a 2.4 @ 8 psi? I mean this is a stock sohc engine and its fwd so traction will be an issue with a bigger turbo. This isn't going to be a drag car. It's a daily driver. Just want to get alittle more out of it.

[seth98esT]

Imo, any 16g would suite a 2.4L 4g64 at low boost very well. With my 2.0L 4g63t and 14b, it still spools too soon for FWD. I spin first, pull second, and if I am exiting a corner a good speed I can spin 3rd as well.

A small 16g, b16g, or even an Evo3 16g would bump the spool up by 500rpm or so and would help with traction. And a 16g will outflow a 14b even at low boost levels.

A t25 would work, you would be pretty much maxing the thing out though at 10psi or so. A t25 on a 4g63t looses efficiency at 15-16psi.

[phizz2k]

Where do you guys tap in for the turbo water lines?


Thats what I've been wondering as well. All the pics I've seen are tapped away from view of the camera.
Good luck on your build.

[DOHCstunr]

the other part about a small turbo
is that ist spools up quick(you lose traction) and it runs out of breath quick(you have no top end)

on a fwd 2.4 both those are bad,

torque is not a problem cause you ahve a 2.4
top end is definatly a prob

with a bigger turbo you will offset spool a bit allwoign you to hook up,
and you will have mad top end cause of the larger wheel.

small 16g standard big 16g both those are fine.
even a t3/t4 in a vtrim would rock for you.




as far as the translators.
get the gen two, its 10x better than a safc and 100x better then the gen 1.

http://www.dsmtuners.com/forums/showthread...7#post151030577

these prices are with the brand new mas included.

trust me wideband tracking is worth every single penny,
not to mention the much much higher resolution fuel adjustments.
on three load levels.
as opposed to jsut two on the safc2.

[Sleepervr-4]

http://www.dsmtuners.com/forums/showthread...7#post151030577

these prices are with the brand new mas included.

trust me wideband tracking is worth every single penny,
not to mention the much much higher resolution fuel adjustments.
on three load levels.
as opposed to jsut two on the safc2.

I saw that and was reading up on it. That is why I was leanin on that setup.

[98ACR]

Agreed the T25 truely is a tiny turbo especially trying to push 2.4L. But what I guess you should have pointed out is that you are staying automatic. In this instance a smaller turbo is better because sooner boost helps counter the lag experienced by an automatic. I'd recommend a 14b for your application. The 16g or t3/t4 is just too big for a low boost application in my opinion. But I'm from the school of big engine/small turbo (a 'la SRT-4) because it makes for a stronger "feeling" car.

[evil-G-nius]

I plan on going with the 16G fo the simple reason of it being that grey area. I dont want anything too small and that will possibly need to be replaced in a year or two from constantly being in boost. Obviously I dont want one too big for serious lag reasons as well as not wanting to blow up the motor (Staying stock). So the 16G would suit quite well for 8-10 psi and responsiveness. Its that mid range.

My question about those however, is which 16G packs more punch? Small or Large and how much of a difference would I notice between em? I think the small 16g is slightly cheaper too so...I dont know

[seth98esT]

A post I made a few months back in the turbo sizing thread hehe. At 8psi and redline, the 18g would be most efficient at the 6200 RPM but would lack the spoolup of a smaller turbo. It must be the design of the 18g wheel that makes it so efficient at such low boost. The next turbo that would come in second efficiency wise would be the Small 16g. With the small 16g it woul have a spoolup simialr to the 14b(maybe 200rpm higher) and be efficient at its boost level on a 2.4L motor

Compressor maps are fun, Im going to learn how to calculate spoolup for each turbo on our motors.

<div class='quotetop'>QUOTE("seth98esT on Compressor maps for the 4g64")</div><div class='quotemain'>OK here goes:

Engine Volumetric Flow Equation
VAF(Volume Air Flow in cu. ft/min) = (Enging RPM x engine cid) / (1728 x 2)

So in a 2.4L

VAF = (6200 x 146.458) / 3456 = 262cfm

Ideal Gas Law/Mass Air Flow
The Ideal Gas Law is a handy equation to have. It relates the air pressure, temperature, volume, and mass (ie, pounds) of air. If you know any three of these, you can calculate the fourth. The equation is written:

P(absolute pressure) V(volume) = n(related to the number of air molecules, which is an indication of the mass (or pounds) of air) R(constant number) T(absolute temp)

Lets assume that we are at sea level.

8psi of boost(psig) = 22.7psia(14.7+8)

The absolute temperature is the temperature in degrees F plus 460. This gives degrees Rankine, or deg R. If it is 80 deg F outside, the absolute temperature is 80 + 460 = 540 deg R.

n(lbs/min)= P(psia) x V(cu.ft./min) x 29 / (10.73 x T(deg R))

Lets say you are running an intercooled setup and temps in the intake manifold are 130F and you are still running 8lbs of boost:

Absolute temperature = 130 deg F + 460 = 590 deg R
Absolute pressure = 8 psig + 14.7 = 22.7 psia

n(lbs/min)= (22.7 psia x 262 cfm x 29) / (10.73 x 590 deg R) = 27.24 lbs of air per minute (ideal)

lbs air per minute actual = 27.24 x 0.85 = 23.16 lbs air/minute



Volumetric Efficiency
If life was perfect, we could fill the cylinders completely with air. If we had 17 psi boost in the intake manifold, we would open the intake valve and get 17 psi in the cylinder before the intake valve closed. Unfortunately, this doesn't usually happen. With some exhaust remaining in the cylinder and the restriction offered by the intake ports and valves the actual amount of air that flows into the cylinder is somewhat less than ideal. The amount that does flow divided by the ideal amount is called the volumetric efficiency.

To take this into account when we calculate flow into the engine, we multiply the ideal amount of air by the efficiency to get the actual amount of air:

actual air flow = ideal air flow x volumetric efficiency

Now the lower your FMIC/cooling system can cool the air by the time it hits the intake manifold, the more lbs air/min you will move. So an intercooled turbo setup vs a non-intercooled setup will vary greatly!

Compressor
The compressor is the part of the turbocharger that compresses air and pumps it into the intake manifold. Air molecules get sucked into the rapidly spinning compressor blades and get flung out to the outside edge. When this happens, the air molecules get stacked up and forced together. This increases their pressure.

It takes power to do this. This power comes from the exhaust side of the turbo, called the Turbine. Not all of the power that comes from the turbine goes into building pressure. Some of the power is used up in heating up the air. This is because we lowly humans cannot build a perfect machine. If we could, all of the power would go into building pressure. Instead, because of the design of the compressor, the air molecules get "beat up", and this results in heat. Just like rubbing your hands together will warm your hands due to the friction between your hands, the friction between the compressor and the air and between the air molecules themselves will heat up the air.

If you divide the amount of power that goes into building pressure by the total power put into the compressor, you get the efficiency of the compressor.

For example, if the compressor is 70% efficient, this means that 70% of the power put into the compressor is used in building air pressure. The other 30% of the power is used heating up the air. That is why we like high efficiency compressors; more of the power is being used on building pressure and less is used heating up the air. You want to be in the 65% and higher efficiency range.

How to read a compression map(that I posted above)
Figure out the pounds of air that you are moving through the engine. We are passing 29.77 lbs/min of air, at inlet conditions of -0.5 psig and 70 deg F. Now correct that flow to the standard temperature and pressure.

Corrected flow = (actual flow x (Tin/545)0.5) / (Pin/13.949)

The standard temperature is 545 deg R, or 545 - 460 = 85 deg F.

o we are correcting the flow from 70 deg F and -0.5 psig to 85 deg F and -0.75 psig.

Tin = 70 + 460 = 530 deg R
Pin = -0.5 + 14.7 = 14.2 psia

Corrected flow = (23.16 x (530/545)^0.5) / (14.2/13.949) = 22.45 lb/min

Now for Mitsu maps, they use CFM, Garret uses lb/min. Every 10 lb/min is equal to 144.72 cfm. So:

CFM = (22.45 lb/min / 10) * 144.72 cfm = 324.9 cfm

So we mark that point on the bottom of the graph, and draw a straight line upward from that point.

The next step is to figure out the compression ratio, using absolute pressures. Using our example, we had 8 psi boost in the intake manifold. Let's suppose the pressure drop from the turbo outlet to the manifold is 3 psi; so the actual compressor outlet pressure is 3+8=11 psig. The air pressure is 0 psig, but since the turbo is sucking air to itself the pressure at the inlet is lower than that. Let's say it is -0.5 psig at the inlet. Then the compression ratio, Pout/Pin is :

Pout/Pin = (11 + 14.7) / (-0.5 + 14.7) = 1.81

So then we find about where 1.81 is on the left side of the graph and draw a line horizontally from that point. Where the two lines meet is where the turbo will operate.

SO using my 1337 skills in MS Paint:


Here the efficiency range for those turbos on the 2.4L:

14b = 72% @ 400cfm


Small 16g = 76% @ 495cfm


Big 16g = Borderline 71% @ 475cfm


Evo3 16g = 74% @ 540cfm


18g = Upper end of 77% @ 540cfm

Now these calculations are all at 8psiag at a 6200RPM redline. They all are pretty efficient for our cars. Technically you want the turbo that is most efficient for our engines. at all RPMs. At redline, the 18g proves most efficient. But that also comes with a higher spool rate which I am not going to calculate simply because I do not know how.</div>

[Sleepervr-4]

seth you are the fuckin man. lol nice info. I think I might order the s16g and throw the t-25 back in the garage.

[seth98esT]

Haha thanks. I cant take credit for the whole thing, just took the information from another site and plugged in the numbers for the 2.4L 4g64 and 8psi.

Im bored at work and am doing the same thing for my 2L 4g63t @ 22psi ha. I bet the Evo3 16g will come out on top.

Everytime I see talk about the Small 16g they always say that it is an underrated turbo(Evo3 16g being the most popular). I assume because its the most efficient out of the bunch at low boost.

If you put your t25 on eGay, I gaurantee you can get at least &#036;100-200 for it as long as its in good condition. Just have to get a good title for the auction like: "95-99 Eclipse Talon Garrett T-25 turbo DSM HONDA"

[Edit]
I screwed up the VE for the calculations above. I just used a standard 85% for the Volumetric Efficiency. I calculated the VE for the 4g63t and it was actually 100.000131%. I will re-post the correct numbers but Im sure they arent too far off.

[peanotation]

so traction will be an issue with a bigger turbo

strictly the opposite. a smaller turbo will give you traction problems because it spools so early and shoves so much torque down your throat. a bigger turbo has more turbo lag and give more of the torque in the upper RPMs.

the T25 is pure shit because the 2g guys have so many problems with it. at 14psi+ it creeps like crazy and doesn't hold boost very well, and that's on a 2.0L. on your 2.4 it's just going to be a nuisance. my 13g was nothing but problems for me on the 2.4: bov always shuddered; couldn't give any throttle without full boost; etc. granted, the 13g is a tiny bit smaller than the T25, but they're relatively the same size. spend the extra dough and get a real turbo, not a toy that will just piss you off down the road.

[B19WHEELS]

Well i can say that my evo3 is a perfect fit for my car. I like to ride around with my big ass wheels so i needed a turbo that could move the big wheels in a instant. Yes im still a automatic and most of the highway races ive been in i havent even had to push the O/D button,just press that gas a little harder the car hasnt even had to down shift from the final gear!! So i would say get and kind of 16g turbo wether a small 16g or a evo 3 or maybe a highly highly ported 14b..

[seth98esT]

Yah take me and Johns setup for instance. Very similar setups: 4g63t swaps, 2.5" intercooler piping, FMIC, ect. Only real big difference(other then mines messy and his is clean enough to eat off of) is the fuel setup and turbos used. He is using an SBR GT50 which is a descent sized 50 trim turbo.

I am using a stock, non-ported 14b. I hit 18psi in first gear no problem at all, jus thtat my tires spin as soon as boost come on(3000RPM or lower). No matter what RPM I am at, the boost comes on so fast the my tires will spin instantly. In second gear I get tire spin in the lower RPMs but not so much in the upper RPM, and 3rd gear is fine.

Now Johns setup, depending on road conditions he will hardly ever spin tire in first and never in second, yet he is making a lot more power then me with his beastly turbo. Since his turbo spools up later it gives him more time to catch traction.

Me and John did race and he definitely beat me. Third gear pull, I got a small jump on him to start but as soon as his turbo started to spool he started to pull away.

http://media.putfile.com/Me-vs-Johns-beast

[evil-G-nius]

After all that I think I'll go with the small 16G. Looks to be the most efficient (outta the maps provided) 76%. I want good response and little lag so this may be the one!

[DOHCstunr]

The evo16g is a great turbo, but they can creep at low boost levels. so just make sure you are at least running a good o2 housing with it.

the evo16g is a great GREAT all aroudn turbo, it spools quick because its rotating assembly is so light. but its still a big wheel so you will have plenty of top end to go with it.

In that video i was drivign with a bad axles(vibrating my teeth loose) and was only running 15 psi w/ plenty of boost leaks haha.

you guys are going to LOVE being able to pass cars w/o having to change gears on the highway. its great!

btw the smoke coming from my exhaust in that vid was from a leftover puddle of oil in the bottom of my intercooler from my 14b that blew up.
I hadn't yet cleaned out the intercooler and whenever i really get on it the presure and aiflow woudl stir up the oil.


I want another race seth!!!
i can't wait for the 1/4!

[seth98esT]

Haha yah me too. I was untuned and just running 17psi(I think). The race would probably still be about the same now though, you would definitely wipe the floor with me.

And the Big 16g is probably the least efficient overall from the bunch. Im not sure why, but Ive read a few places that people dont like that turbo for whatever reason.

[qnz]

bumping an old post

Seth, wehre did you get your information from? Not saying youre wrong or anything. Maybe my understanding is wrong, but isnt the more efficient if the efficiency lines are on the outside of the middle ring? Where the efficiency lines intersect on your graphs is the max possible output the engine can make (redline @ 8 psi). So on turbos like the 18g, where the efficiency lines meet, the efficnency is maxed out but there is still more power to be gained from the turbo. wouldnt it be more efficient if the max torque->max power ran thru the higher efficiency rings, like 75%->77%->75%.

also, redline on the i4 8g is 6000 rpm. max torque is achieved at 3700 rpm and max power is reached at 5500.