63mm TB

[XfireZ51]

I am moving forward on porting the plenum and IHs. I also have a 63mm TB. Haven't checked yet but is it necessary to port the TB openings on the plenum to match the 63mm TB or are they large enough already?

[lbszr]

The plenum port on mine was 1/16 inch or so smaller than the 63mm, so it got match ported to the tb. gasket doesn't match either.

[XfireZ51]

Thanks!

LGaff,

I know you have a 63mm on yours. Can you tell if it is port matched or left alone? Is the port opening smaller than the TB?

[lbszr]

I matched the ports to the TB and also the air horn needs opened up to match also.

[kenthompson]

Man, I'm looking at the plenum and those secondary holes are HUGE! What is the difference going to 63MM?

[phrogs]

It should be port matched on the plenum to the throttle body I mean whats the point if you dont port match them together?

[Aurora40]

Man, I'm looking at the plenum and those secondary holes are HUGE! What is the difference going to 63MM?
If you mean specifics, I believe stock is ~58mm secondary ports. So the difference is 5mm in diameter. If you mean what is the power difference, I don't know.

As an aside, two 63mm TB's and the single 23mm would have the same area as a 92mm single TB.

[Locobob]

The stock plenum throttle bores are 59.5mm in diameter. You should open them up to 63mm otherwise your wasting your money on the larger throttle body.

[LGAFF]

I just checked my car, it has the 415DRM package....


TB measures to 63mm

Intake opening 60mmm???????????????????????


Good catch Dominic! I assumed they would have opened it up since the intake was extrude honed, etc. I'll put that on the list.

LGAFF
92 ZR1
#234

[Zr1 Destroyer]

Get in touch with Greg V. in Oklahoma.....he did nj's last year and was the largest one has has ported to date! It's so nice lookin it was a shame to mount on the car instead of using it for wall art!;)
http://i42.photobucket.com/albums/e346/NITROUSJUNKIE/tb.jpg
....and the finished results......
http://i42.photobucket.com/albums/e346/NITROUSJUNKIE/tb2.jpg

[Aurora40]

Man, did he have to shave two of the bolt heads down a lot? That's some serious bores on that thing!

[Zr1 Destroyer]

Man, did he have to shave two of the bolt heads down a lot? That's some serious bores on that thing!A little bit, but it took about three minutes with an air cutter! You should here it fire up....it sounds like it's gonna suck the shirt right off yer chest.:-D

[XfireZ51]

I just checked my car, it has the 415DRM package....


TB measures to 63mm

Intake opening 60mmm???????????????????????


Good catch Dominic! I assumed they would have opened it up since the intake was extrude honed, etc. I'll put that on the list.

LGAFF
92 ZR1
#234

Well make that 2 more holes to port. :wink:

[LGAFF]

Chip Foose can restore a car in a week, it takes me 6 months to port
an intake.

16 plenum runners
16 IH runners
8 head ports
2 TB ports

Thats and easy 50 hours of :censored: work.

LGAFF
92 ZR1
#234

[bradslt5]

yeah but foose has alot of helpers and free parts too. but he does do a nice job. wonder what he would do with a zr1 ????????????????????????

[LGAFF]

Opened up the left side to 63MM: Big difference, however the are obstructions behind the TB openings.

http://i134.photobucket.com/albums/q115/lgaff/DSC02410.jpg

LGAFF
92 ZR1
#234

[Locobob]

Opened up the left side to 63MM: Big difference, however the are obstructions behind the TB openings.

http://i134.photobucket.com/albums/q115/lgaff/DSC02410.jpg

LGAFF
92 ZR1
#234

You can grind a good bit of material off the obstructions - be careful with the coolant passeges though.

[XfireZ51]

LB,

Got any pics of the port job you did on the tb openings?

[lbszr]

LB,

Got any pics of the port job you did on the tb openings?

I bought the TB already ported.
This is the ported air horn on a stock TB to show the difference, it's actually almost 1/8 inch that needs to be ported to match, the plenum port looks the same as stock, just bigger.

This just made me realize I have a problem though with the air horn accuired from the site, cause it has no vaccum port in the bottom for the small vaccum line. Any idea's on that?

http://i188.photobucket.com/albums/z41/myphotos123456/cid__021808_022557.jpg

[Aurora40]

This just made me realize I have a problem though with the air horn accuired from the site, cause it has no vaccum port in the bottom for the small vaccum line. Any idea's on that?
I think only the 1990's had that. I'm pretty sure for '91 the vacuum stuff moved around a bit.

[Locobob]

I think only the 1990's had that. I'm pretty sure for '91 the vacuum stuff moved around a bit.

Yep - 90 only. The boss is still there on the later castings though - you could drill it out and add a fitting.

[lbszr]

Yep - 90 only. The boss is still there on the later castings though - you could drill it out and add a fitting.


Drilling and putting in a fitting with loctite 620 worked good. Didn't feel like figuring out the replumbing.

[Locobob]

I'm doing a port job for Frank T. right now including enlarging the throttle bores to 63mm. Here is what the difference between stock size and 63mm looks like - area marked in red is to be removed.

http://www.pnwzr1.net/Robert/Plenum_TB.JPG

http://www.pnwzr1.net/Robert/Plenum_TB1.JPG