HKS Turbo's vs Garrett Turbo's...

[Roy]

Evan, can i ask who setup up your Wolf computer?

[rb20-calais]

noone yet,

i am gonna get one of my mates brothers to wire it up and then i will be getting cooler piping, turbo lines and dyno tuning done at Ricol performance in Peakhurst.

they are good blokes

Evan

[RS500]

Originally posted by rb20-calais

RS500,

I think that I will go with the 0.64AR exaust housing after these comments. I could always get it machined more at a later date if I wanted.

When you say a lot of boost creep before 10psi what exactly do you mean?

Also when I get my wastegate actuator should i get one with a 15psi spring in it and then bleed to 18-20psi? I have a wolf 3d and i am pretty sure it has an inbuilt EBC, anyone know much about this?

Thanx

Evan

Evan,

i think the .64 should work good for the street.

my friend's turbo had a weak actuator spring which means it was opening the wastegate and by-passing exhaust gasses at low boost causing slow boost build-up.

re: wastegate actuator, try and get teh highest you can get for the boost u want to run, and then bleed it off as you mentioned.

sorry, i don't know much about the Wolf 3D.

[Sydneykid]

Sorry RS500, back to back race meetings took me away and couldn't answer your questions.....

For the RS500's Cosworth made a number of specifications of rods and pistons. We had to use "standard" parts, some were just more "standard" than others.

Hi Steve, yep I reckon the twin 2530's on the GTR where the best all round (road, drag, race) set up I have driven. It had a nice high average power (not a single big max at 1 rpm point) from 4,000 rpm to 8,500 rpm.

More recently I drove a genuine N1 R32 GTR (freshly rebuilt) and it had the N1 (Garrett BB, steel turbine, WC) turbos, I reckon it was damn near as good as the 2530's. It dynoed at 375 fwkw, which is pretty much 600 bhp, with only PFC and a turbo back twin exhaust (one from each turbo) running on Elf Turbomax. I was EXCITED!

This is a great thread, hope this post added a bit to it

[Freebaggin]

Sydneykid,

You see on Garrett and/or HKS tables you can have turbos with various combos of compressors, turbines and housings that can have the same ultimate power output, for eg;

GT30/T04S at 550HP

Comp. 0.7 A/R, 56T, 2.25"/3.00"

Turb. 1.06 A/R, 84T, 2.16"/2.36"

GT30/GT40 at 550HP

Comp. 0.7 A/R, 56T, 2.41"/3.22"

Turb. 0.63 A/R, 84T, 2.45"/2.68"

Another example in the HKS range, GT2540R at 370HP and a GT2835 at 380HP using different combos.

I fully understand the concept of A/Rs etc etc, but my question is what different characteristics would say the above Garrett turbos have compared to one another, even though at 1 bar they have the same nominal power level.

Would one have more power at lower boost whereas the other can keep flowing well at higher boost?

Also which combo would spool faster at the same boost setting.

Freebaggin.

[RS500]

Originally posted by Sydneykid

Sorry RS500, back to back race meetings took me away and couldn't answer your questions.....

For the RS500's Cosworth made a number of specifications of rods and pistons.  We had to use "standard" parts, some were just more "standard" than others.

No probs SydneyKid.

what do u mean by the comment above about standard and more standard parts??

would be able to tell me what wheel trims and housings the RS500's used to make the power they did back then?

[Freebaggin]

Any takers on the combo question?

[Steve]

I'll give it a shot:)

the hp rating is talking about the compressor.

the turbine size will dictate when the turbo comes on boost in relation to the cars rpms.

This will of course vary depending on what he cc of the engine is, how much load, flow characteristics of the engine - BUT put both on the same engine and one will make boost alot lower in the rev range. The bigger the AR, the more exhasut flow required to spin the turbine wheel, and also as an added benefit, less back pressure.

If the turbine AR is too small for the compressor, one side effect can be surge as far as I know, why? this is where I start sort of guessing, so standing by to be flamed. A smaller turbine AR will mean greater back pressure, which would make it harder for the compressor to flow the air into the cylinders = surge????? Please if anybody knows if I am completely off track with this one, and can explain why - do.

Also with smaller turbine AR, the wastegate may need to be bigger to prevent boost creep as it will need to flow alot more gas than if a larger housing was fitted.

To me it is somewhat of a mystery because there are so many unknown variables when putting a package together and I dont have the money to do the research into finding out what compressor and what turbine would work exactly the way I want with my mods.

I have bought a turbo that will produce the power I want, I have decided on using a smallish turbine housing to bring boost on earlier in the revs, using a wastegate that is rated to flow above my target hp, and am prepared to change the turbine housing to free up the top end if it starts to choke, or if I start experiencing surge when I start winding in extra boost:)

[Freebaggin]

Thanks Steve, fair enough.

However the HP rating is not for the compressor only, it is for the turbo combination as a whole that takes into account the turbine A/R. Smaller A/R lower the HP rating on the Garrett charts.

So the question still is with the same ultimate HP rating at the same nominal boost, how does each combo behave across various boost pressures and engine RPM.

The turbine size is of course important for boost response but how about the difference between a big turbine in small A/R housing vs small turbine in big A/R housing as per the examples above???

[Sydneykid]

Hi RS500, when we started racing them they had a certain spec of piston and rod. As the racers world wide chased even more power and rpm, they started to blow up, lots. So Cosworth made stronger bits for them. This went on for a number of generations of parts, as outlined in the racing parts manual. At the same time, there were upgrades to the road parts list. The part numbers were basically the same, but they had different suffixes.

We had, at one time, a European team's RS500 engine and it had different (stronger) rods and crank than ours. We asked Cosworth and they said both were "standard" parts, so we coined the phrase that ours was just a bit more "standard" than theirs.

I never played with the turbos, they were sealed from Cosworth. Came in a box, put them on, blow them up, put them back in the box and send them back to Cosworth. If you didn't send the old turbo back, they would not send you a new one.

When the race cars were sold, the parts manuals went with them, so I can't help you anymore than that.

Hi Freebaggin, I can read a compressor map and choose a compressor and cover to suite my application. I then tell the turbo expert (we use GCG) what I have chosen and the engine spec and armed with this information he picks the turbine and housing to suite.

The numbers you have quoted (AR ratios, trim numbers etc) aren't the full story as the compressor and turbine blades have quite different aerodynamics depending on their shape (pitch, no of blades, depth etc). So a HKS3040 may have exactly the same quoted dimensions as a Garrett GT3040BB, but will perform quite differently.

Have a read of Corky Bell's books on turbocharging, there is nowhere near enough space here to do this subject justice.

Hope that helps

[BOOSTD]

I have been experimenting with a T3/4 hybrid.

Started life as a VG30BB .6AR / .81AR Ex

1.Installed a Vtrim t04 compressor

=15psi boost by 2600

Now that looks impressive however mega surge is the out come.

After alot of research on how to read compressor maps, I can calculate that my engine needs to reach 15psi by 4000rpm or later to pass the surge limit. Also Corky bell states that a maximun of 2.5 times the boost preasure is allowed in the exhaust mainifold or on cam overlap you will get exhaust gas flowing back into the cylinders. I found my car made no more power with any more boost over 13psi. I concluded that my 42mm ceramic turbine was on the small side on most likely causing a very high restriction.

2. Bored out the turbine housing(snout) by 4mm

=15psi by 3600 rpm, car now frys my 275s at a quarter throttle in second. Standard fuel system is not keeping up now and is leaning out with any extra boost. Turbo still surges in third.

3. this week! Will take another 2mm out of the turbine snout. (49mm) hopefully boost will hit 15psi by 4000rpm or a tad later.

New technology-

Had the chance to dribble over a Apex RX6 turbo for a SR20. This Turbo is capable of 300rwkw.

The comp cover was massive at least .7AR

What the !!!! exhaust housing was so so small... I'm taking CT26 size however the turbine would have been 55- 60mm Apex defenately know something HKS don't..........

[JimX]

BOOSTD, where is the turbo "snout" you refer to above? Is this the bit that bolts onto the dump pipe? This is the part of my turbo which I am going to get bored out to 3" and a dump pipe to suit also installed.

[BOOSTD]

I am refering to the part of the housing that surrounds the turbine. 3" would be nice would flow 1000hp

[Steve]

BOOSTD, is the turbine housing smaller than 0.61? Thats whats hanging off the back of my 3037 - looks waaaay too small:)

God I hope it isnt:D

How did you get he turbine housing bored out? Extrusion hone?

Seems to be doing the trick, good luck with the next one.

[BOOSTD]

.81

I am sure .61 should be fine. I bet the turbine is bigger than 42mm- thats were the power is to be had.

I used a lathe. extrusion hone would have been ok 2 but couldn't be stuffed setting it up.

[RS500]

Steve,

i believe the .61 would be a little too small for an RB25DET. You'll ideally want to go with the A/R .73 for the street. This will give u a nice balance b/w response and top-end flow/hp.

[Freebaggin]

I'm sure you can if you had a big housing that holds a big turbine and it was0.61, it would be fine on an RB25DET. The turbine size on a 3037 is 60mm/55mm so I reckon 0.61 will be perfect.

The housing AND turbine on Boostd turbo is significantly smaller if the turbine is 42mm (major or extuder?), so at 0.61 it caused surge.

BTW BOOSTD, did the RX6 have an int. or ext. wastegate?

Steve, do you have a picture of the turbo side on so we can see the size differential between the compressor and turbine housings?

[Steve]

RS500, I have a 0.73 lined up for a swap if the housing is too small (fortuneately).

Freebaggin, attached is a side view - dont laugh its farking tiny:) I hope you are right about the size, seems a bit strange that HKS would sell it if its no good, will know soon enough.

[Freebaggin]

Well you know what they say, it's what you do with it that counts!

[BOOSTD]

Freebaggin, my exhaust A/R is .81 and turbine is 42mm exducer. The RX6 had an external gate.