450-500HP turbo, Internal or External Gate?

[EnricoPalazzo]

this is the compressor map for the t04e-60 trim.

it is close to surge line at 1.1bar and 4000rpm but i dont think it will surge.

What are your thoughts.

One thing im not sure about is how to calculate volumetric efficiency at certain RPM. Ive only guessed them as shown in my inputs.

[EnricoPalazzo]

Here is another compressor map, this one is 62-1.

It has alot of points in its major efficiency regions aswell.

ahh im confused...

[EnricoPalazzo]

Instructions for turbo calculator:

Turbo Map can be used to plot a Turbocharged engine air flow against various compressor flow maps, to determine what compressor wheel best suits your engine.

The points fields are used to plot the air flow at different RPM and boost conditions. It is not necessary to fill in all points fields, just one if you wish.

If the map is too small a bigger map will be shown. You will need to then press the "Calc" button again to plot the points.

The following is an example of using the points fields.

RPM Boost VE Comp Efficiency

Point 1 7000 80 80 60

Point 2 4000 80 90 72

Point 3 2000 5 100 60

Point 1 is the maximum engine RPM.

Point 2 is the RPM where maximum boost is achieved. ( Wastegate starts to control boost pressure)

Point 3 is the RPM where boost starts.

When selecting a compressor that is the best match for your engine, select a flow map where the point the maximum boost is first achieved ( Point 2 in this case) is close to the surge line

This will ensure maximum compressor efficiency through the engines maximum torque RPM.

[Sydneykid]

this is the compressor map for the t04e-60 trim.

it is close to surge line at 1.1bar and 4000rpm but i dont think it will surge.

What are your thoughts.

One thing im not sure about is how to calculate volumetric efficiency at certain RPM. Ive only guessed them as shown in my inputs.

As I said, your plot 3 is the problem, think about how often you go through or stay in the 3,000 to 4,000 rpm area.

My rule of thumb for volumetric efficiency on a DOHC 4 valve engine is 90 to 95% depending on what's done. A fresh engine with cams and porting etc is closer to 95%, compared to an old engine with stan'd cams and cast ports that would be closer to 90%. Simple

[Bl4cK32]

I have done it in NSW, a bunch of us got together and the emissions testing facility was closed for 4 years as a result. I have also "been to court" on a couple of other issues (mostly successful) and I have one on at the moment over Speed Cameras and their maintenance. So I don't just talk about it.

Sorry for the hijack Enrico....

But - Steve is trying to do something about it. I don't know how far he has gotten with it but i can assure you if i could, i would. It Seems the Government here in SA is setup to cover their own arses, and if you don't believe me, come try for yourself Gary.

Not saying i wont, but there are cases that have been unsuccessful before

edit/ Regency isnt just a testing facility either. Its only one of a couple of places that are authorized to do vehicle safety checks in SA. There is no "pay for your mods" scheme in SA. They even have the right to dissagree with engineers reports that state the car meets EVERY requirement, and still defect you, even though they dont hold a degree themselves.

Sounding fair now? Come try Gary, I'll go to court wit you

[Sydneykid]

Sorry for the hijack Enrico....

 

But - Steve is trying to do something about it. I don't know how far he has gotten with it but i can assure you if i could, i would. It Seems the Government here in SA is setup to cover their own arses, and if you don't believe me, come try for yourself Gary.

 

Not saying i wont, but there are cases that have been unsuccessful before

Don't get me wrong I am not saying it's easy, because it isn't. Sometimes loosing the case is not the real issue, what you are trying to do is embarass the Govt. They want to be elected next time, so bad publicity and the opposition spokesperson can be your best weapons. :ak47:

You are right, all govt's are "set up to cover their arses" but that is your best tactic, expose their arse. You don't have to kick it, just expose it. :shake:

The media will kick it for you.

[EnricoPalazzo]

As I said, your plot 3 is the problem, think about how often you go through or stay in the 3,000 to 4,000 rpm area.

My rule of thumb for volumetric efficiency on a DOHC 4 valve engine is 90 to 95% depending on what's done.  A fresh engine with cams and porting etc is closer to 95%, compared to an old engine with stan'd cams and cast ports that would be closer to 90%.  Simple

thanks for the ve estimate. So do i use it throughout the rev range...?

Also u pointed out to me a surge problem at point 3. How do i not get a point that will surge at point 3?

[EnricoPalazzo]

hmm i changed some of my points and i see what ur talkin about.

it seems almost every compressor map, it will surge except for the 62-1 trim.

I have to check all the inputs i have done, but does this sound correct?

[aqik33]

A volumetric efficency of 90% and above is slightly optimistic, I would say 85%, better to be safe than sorry. And remeber max volumetric efficiency occurs at peak torque point NOT peak power!!

Peak torque rpm of a standard RB25det is _?

Thats its max volumetric efficency point.

[Sydneykid]

A volumetric efficency of 90% and above is slightly optimistic, I would say 85%, better to be safe than sorry.  And remeber max volumetric efficiency occurs at peak torque point NOT peak power!!

Peak torque rpm of a standard RB25det is _?

Thats its max volumetric efficency point.

Not wishing to argue here, but just support my rule of thumb. I have seen the test data from Nascar done in 1978 that shows a small block Chevy sits at 85% volumetric efficiency. Smokey Yunik in the late 70's also tested a Ford Windsor V8 and ended up at 86%. Since these are both 4 barrel carburetted engines with 2 valves per cylinder and pushrods, I have no problem believing a DOHC 4 valve fuel injected engine isn't going to achieve another 4%. Then we have the now arguably far superior piston ring and bore composition, not to mention the aerodynamic improvement in valve flows.

So I will stand by my 90% to 95% rule of thumb, at least until I see tested evidence otherwise from a reputable source.

[bigcarl]

thanx for the detailed info sydney kid, im still runing stock cams / head no porting. ive just fitted a stainless steel manifold for the internal wastegated gcg turbo it flows 6 into 4 into 2 just before the flange i think its a copy of a hks manifold, havent had ecu remapped yet but there seems to be alot more midrange torque and top end power, will post my results after i get the car tuned.

[drunkenmaster]

Quick question, what is the A/R of the GCG 450~500hp upgrade?

Thanks

[Abo Bob]

What is A/R?

[bigcarl]

a/r60 ? sydney kid?

[Sydneykid]

Quick question, what is the A/R of the GCG 450~500hp upgrade?

Thanks

I don't know, I have deliberately never measured it.

[drunkenmaster]

Hmmm...anyone ever ran one on a 3.0? if so, when was it hitting full boost by?

[B-Man]

What is A/R?

[/color]

A/R

               

·                  A/R describes a geometric property of all compressor and turbine                  housings. Increasing compressor A/R optimizes the performance                  for low boost applications. Changing turbine A/R has many effects.                  By going to a larger turbine A/R, the turbo comes up on boost                  at a higher engine speed, the flow capacity of the turbine is                  increased and less flow is wastegated, there is less engine backpressure,                  and engine volumetric efficiency is increased resulting in more                  overall power

               

taken from the ATP Turbo website - click here

So, the A/R ratio of the exhaust housing refers to the size and shape of the scroll that is cast into the housing. It basically determines how restrictive the housing will be, versus how quickly the turbine will spin up. A lower A/R ratio (smaller scroll area, A) results in a more restrictive housing. This restriction speeds up the exhaust gasses and increases the amount that the gasses will expand. It's the speed and expansion of the gasses that causes the turbine to spin. So with a low A/R ratio, the turbine will spin up quicker, but as engine output and rpms increase, the restriction of the housing begins to build up too much back pressure on the engine, which reduces performance. A good rule of thumb for when there is too much back pressure is when the pressure in the exhaust manifold is more the half of the pressure in the cylinder. So basically, a larger A/R ratio will improve your engine's top end, while losing some mid range power and increasing turbo lag. A smaller A/R ratio will help the bottom and mid-range, but may effect the top end.

Taken from the TurboNation website - click here

[Abo Bob]

Thanks.

[JimX]

Has anyone got any experience with running a Garrett t3/t04e hybrid turbo.

They seem to be good for around 500hp, and are not meant to be very laggy.

Does anyone know?

I'm pretty sure that's what I have. I don't have many details because it was already there when I bought the car, and was just advertised as a "450hp T04 turbo". A guy from Garrett in Chipping Norton later identified it as a T04E, but he didn't mention the rear housing which internally gated. So I presume it's a T3/4 hybrid, although the exhaust housing doesn't look the same as the VL turbo housings I've seen.

Not having driven a turbo car with a state-of-the-art HKS or GT Garrett turbo I can't really comment on the lag, but I've been a passenger in an R33 with a stock turbo and mine doesn't seem too bad in comparison. If I launch at about 3000rpm it does so decently without bogging down. I can't remember when exactly full boost (15psi) comes on but I've mentioned it somewhere in another thread. I think around 4000-4500rpm.

I had the car tuned with an S-AFC before at 1 bar, and it got 215rwkw. This wasn't quite maxing out the injectors or the AFM. After I swapped the S-AFC for a PowerFC, it then maxed out the injectors and AFM at 0.9 or 1.0 bar. So at a rough estimate I would say that it's now getting around 215rwkw or a tad more at 0.8 bar.

It's not the turbo I would have chosen if the car didn't come with it, unless it was dirt cheap and I was poor, which it is and I am. I'm guessing the previous owner thought the same thing. Depending on price I think it's a good turbo, and you could probably get one for half the price of a GCG 450hp factory rebuilt one. The exhaust housing is rather small, if it is indeed rated to 450hp I could probably get more out of it by getting a bigger exhaust housing for it. The compressor is .6 AR.

Other things to consider are you will need a new dump pipe, so try to find one that comes with it to save some money.

[EnricoPalazzo]

Thanks JimX. I think there are too many surge related problems when it comes to these big hp t3/t4 hybrids, so im just gonna start looking at tried and proven methods, rather then re inventing the wheel as such.