Go Back  CorvetteForum - Chevrolet Corvette Forum Discussion > C4 Corvettes, 1984 - 1996 > C4 ZR-1 Discussion
Reload this Page >

What happened to those LT% Siamesed Intake Runners?

Notices
C4 ZR-1 Discussion General ZR-1 Corvette Discussion, LT5 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track

What happened to those LT% Siamesed Intake Runners?

 
Old 04-20-2018, 12:52 PM
  #21  
tpepmeie
CF Senior Member
 
Member Since: Nov 2001
Posts: 178
Thanked 0 Times in 0 Posts
Default

A 427 at 7000 rpms pulls almost 1.5” manifold vacuum through a dual 63.5mm ported TB. At least mine did. On another engine, 368, was around 1.0” vac through a similarly ported TB.
tpepmeie is offline  
Old 04-20-2018, 01:03 PM
  #22  
Dominic Sorresso
CF Senior Member
 
Dominic Sorresso's Avatar
 
Member Since: Sep 2000
Location: Bartlett IL
Posts: 5,090
Thanked 114 Times in 92 Posts
Default

Tom,

As Todd has pointed out, of course the LT5 is going another ~ 2000rpm than an L98 or an LT1 motor. Power peak on mine is nearly 6900rpm. And yes its very close to 100kPa at WOT depending on altitude/temp. So the 63mm is utilized.
My manifold is not siamesed, but it is ported to
36mm + as best as the plenum casting will allow.
Dominic Sorresso is offline  
Old 04-20-2018, 02:53 PM
  #23  
Tom400CFI
CF Senior Member
 
Tom400CFI's Avatar
 
Member Since: Aug 2004
Location: Park City Utah
Posts: 13,808
Thanked 586 Times in 520 Posts
Default

Originally Posted by Dominic Sorresso View Post
Tom,

As Todd has pointed out, of course the LT5 is going another ~ 2000rpm than an L98 or an LT1 motor. Power peak on mine is nearly 6900rpm. And yes its very close to 100kPa at WOT depending on altitude/temp. So the 63mm is utilized.
My manifold is not siamesed, but it is ported to
36mm + as best as the plenum casting will allow.
O.K. So no, a bigger TB or more TB's isn't going to help in a meaningful way on that engine. Thanks for posting that data to clear that up.

That "427" above? Yikes. Something seems amiss there. 1.5" vacuum??



.

Last edited by Tom400CFI; 04-20-2018 at 02:58 PM.
Tom400CFI is offline  
Old 04-20-2018, 05:24 PM
  #24  
tpepmeie
CF Senior Member
 
Member Since: Nov 2001
Posts: 178
Thanked 0 Times in 0 Posts
Default

[QUOTE=Tom400CFI;1597039676
That "427" above? Yikes. Something seems amiss there. 1.5" vacuum??

.[/QUOTE]

Yes the problem is the TB is too small. Seen it more than once on engines which pump a lot of air. I think we’ve taken this thread down a hole the OP didn’t intend. Sorry.
tpepmeie is offline  
Old 04-26-2018, 06:48 PM
  #25  
Paul Workman
CF Senior Member
 
Paul Workman's Avatar
 
Member Since: Oct 2004
Location: "Below I-80" Illinois
Posts: 5,528
Thanked 200 Times in 186 Posts
Default

Originally Posted by Tom400CFI View Post
O.K. So no, a bigger TB or more TB's isn't going to help in a meaningful way on that engine. Thanks for posting that data to clear that up.

That "427" above? Yikes. Something seems amiss there. 1.5" vacuum??



.
For what it is worth, Marc says the 63mm TB is worth ~ 6 hp on a 5.7L motor with full upper/lower (i.e., "510") porting. I ran an analysis of air flow vs HP and cam up with exactly a 6 hp increase, provided the plenum too was opened to 63mm.
Paul Workman is offline  
Old 04-27-2018, 12:08 AM
  #26  
Dominic Sorresso
CF Senior Member
 
Dominic Sorresso's Avatar
 
Member Since: Sep 2000
Location: Bartlett IL
Posts: 5,090
Thanked 114 Times in 92 Posts
Default

Wonder what the results are given additional lift and duration.
Dominic Sorresso is offline  
Old 05-09-2018, 08:28 PM
  #27  
USAZR1
CF Senior Member
 
USAZR1's Avatar
 
Member Since: Jan 2000
Location: Wichita Falls TX
Posts: 4,934
Thanked 53 Times in 45 Posts
Default

Greg Van Deventer built my siamesed plenum, for the stock displacement LT5 in my 1990 #952. Engine had Jeal intake cams and headers so I had it engraved.

USAZR1 is offline  
The Following User Says Thank You to USAZR1 For This Useful Post:
1993C4LT1 (05-09-2018)
Old 05-09-2018, 08:48 PM
  #28  
1993C4LT1
CF Senior Member
 
1993C4LT1's Avatar
 
Member Since: Oct 2011
Location: Dallas Texas
Posts: 14,301
Thanked 353 Times in 311 Posts
Default

Damn
1993C4LT1 is online now  
Old 05-21-2018, 08:51 PM
  #29  
Ronstar
CF Senior Member
 
Member Since: Jul 2012
Location: Michigan
Posts: 247
Thanked 53 Times in 30 Posts
Default

Here’s mine. 421 ci. Not the best picture .....


Last edited by Ronstar; 05-21-2018 at 09:04 PM.
Ronstar is offline  
Old 01-13-2019, 06:25 AM
  #30  
Vette Guy
CF Senior Member
 
Vette Guy's Avatar
 
Member Since: Jul 2002
Location: San Antonio TX
Posts: 165
Thanked 8 Times in 7 Posts
Default

Yes, there's an extra 100 shot installed.
Vette Guy is offline  
Old 01-27-2019, 08:23 AM
  #31  
Rkreigh
CF Senior Member
 
Member Since: Dec 1999
Location: Alexandria, Virginia, USA VA
Posts: 7,810
Thanked 74 Times in 67 Posts
Default

I'm thinking ITB as big mods on the factory intake are #@ pricey

I believe I can hack up and mod the inj housing to straighten out the flow and you'll have plenty of intake tb flow by using a lay over crab style itb like the old bb chevy did

for the chapparal team, those old calliope stacks really did make the bb chevys sing and with the right progressive linkage I sure would like to try it out!

all my dollars are just going to get my lsv back on the road with "current technology" but I'm looking to do this if feasible down the road.
Rkreigh is offline  
Old 02-05-2019, 06:50 PM
  #32  
93Polo
CF Senior Member
 
93Polo's Avatar
 
Member Since: Oct 1999
Location: Guinness Its whats for B'fast JAWGA
Posts: 30,562
Thanked 135 Times in 128 Posts
CI 3-4-5-9 Veteran
Default

Originally Posted by cuisinartvette View Post
one pictured sure resembles the 502 GM ramjet
That looks to be the Gen III motor which never made it into production.

https://www.enginelabs.com/engine-te...s-alive-again/

Originally Posted by Rkreigh View Post
I'm thinking ITB as big mods on the factory intake are #@ pricey

I believe I can hack up and mod the inj housing to straighten out the flow and you'll have plenty of intake tb flow by using a lay over crab style itb like the old bb chevy did

for the chapparal team, those old calliope stacks really did make the bb chevys sing and with the right progressive linkage I sure would like to try it out!

all my dollars are just going to get my lsv back on the road with "current technology" but I'm looking to do this if feasible down the road.
No doubt and it would be beautiful wish I had pics of the Lotus Elise GT1s at Sebring who ran LT5 derived motors with ITBs.
93Polo is offline  

Thread Tools
Search this Thread
Quick Reply: What happened to those LT% Siamesed Intake Runners?


Sponsored Ads
Vendor Directory

Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: