Paging Patrick....70 compressor housing performance differences

[Blazer406]

Looking at several used 70 turbos.... each with different compressor housings.

I am attaching the different pics...

What is the difference... and which is more desireable?

It appears the A/R on one of the Garretts is .60... the other is a .65.... the other one with no visible markings..... looks just like a buddies 74GTQ he has.... at least the compressor housing does...

Is one more desireable than the other?

 

[John Wilde]

The first one looks like a S Type Cover, the second looks like an E Type Cover, the third looks like a H Type Cover.

-E Cover is 3 in and 2 Out
-S Cover is 4 in and 2.5 Out
-H Cover is 4 in and 3 Out

The bigger covers are less restrictive at higher PRs.
Patrick will be able to give you more specific information.

 

[John Wilde]

BTW the smallest cover I would use on a 70MM Turbo is the S Type.
The H is probably a better choice if you have 3 inch intercooler piping.

 

[Blazer406]

According to the sellers (which might not know)....

The newer Garrett is supposed to be a modified inlet... but 4" inlet.... 2-1/2" outlet...

The older Garrett... is supposed to be a 3" inlet....2-1/2" outlet....

The unmarked one.... just like my buddies 74 GTQ.... is supposed to be 4" inlet... 3" outlet....



Question.... will a 4" inlet turbo clear the IAC? I have a 3-1/2" MAF pipe... and it was decently close on a TE60...

 

[John Wilde]

You will need an IAC Angle Kit...

CHAMPION Racing Heads

That should do the trick!

 

[Blazer406]

I do have the angle IAC thingy.... I practically had no choice when I went to the 3-1/2" Big Mouth CA Kit....

I assume the H cover will fit then...... looks like that gets extra consideration... I wonder how much HP difference at say 25 psi boost.....?... 28 psi?

 

[Blazer406]

Looking at this site:

PTE Turbo's page

It appears if you were to compare the T64E to the PT66.... they have the same 66 mm compressor wheel.... the same turbine wheel...but the T64E has a 3"/2"..... and the PT66 has a 4"/3". The compressor covers appear to be the major difference... According to PTE.... the T64E was rated at 700HP... but the PT66.... 755HP...... +55 HP (potential) from just a larger compressor cover.

I would think similar gains..... maybe greater.... would be if you were to compare the 70mm series of turbos.....

On a side note... the larger compressor cover seems to want 100 - 200 more stall RPM...... as I guess would be expected from what I read..... which suggests... the larger compressor housing has some effect on stall requirements... but not as much as the turbine housing would....

Make any sense?