409 C.I. LT-1
Thread Starter
Instructor
Joined: Mar 2003
Posts: 176
Likes: 0
From: Holtsville NY
409 C.I. LT-1
I know TPIS has built one and I know it is a 4.100" bore and 3.875" stroke, but I don't know what the pros and cons are.
Why don't I see anyone with this combo"
I assume the price is prohibitive, or the pistons are hard to come by?
Does the bore push the block too far?
It would see that if you want a NA motor than displacement is king and this would rule.
Bye the Bye the website I found info on the TPIS 409 is
http://www.geocities.com/MotorCity/7610/dyno.htm
Thanks for any info
Why don't I see anyone with this combo"
I assume the price is prohibitive, or the pistons are hard to come by?
Does the bore push the block too far?
It would see that if you want a NA motor than displacement is king and this would rule.
Bye the Bye the website I found info on the TPIS 409 is
http://www.geocities.com/MotorCity/7610/dyno.htm
Thanks for any info
Le Mans Master
Joined: Oct 1999
Posts: 9,713
Likes: 3
From: Sachse Texas
Cruise-In I Veteran
Cruise-In II Veteran
Re: 409 C.I. LT-1 (Epyon127)
First off, for an LT1 it is not a 4.1" bore with a 3.875" crank stroke. It is a 4.030" bore with a 4" crank stroke. You would have to do a LOT of work to an LT1 block to get it to a 4.1" bore as most will not even bore out to +.060".
The problem with them is increased piston speed, shallow piston ring height, and it can be expensive to machine the block for the 4" stroke.
The problem with them is increased piston speed, shallow piston ring height, and it can be expensive to machine the block for the 4" stroke.
Melting Slicks
Joined: Jul 1999
Posts: 2,875
Likes: 0
From: Olive Branch (Memphis suburb) MS
Cruise-In II Veteran
Re: 409 C.I. LT-1 (Vette92)
First off, for an LT1 it is not a 4.1" bore with a 3.875" crank stroke. It is a 4.030" bore with a 4" crank stroke. You would have to do a LOT of work to an LT1 block to get it to a 4.1" bore as most will not even bore out to +.060".
it can be expensive to machine the block for the 4" stroke.
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
Re: 409 C.I. LT-1 (Epyon127)
TPIS did build a 409 CI LT-1 in 1997 and they did bore the block .100 over to arrive at a 4.1 bore and 3.875 stroke for 409 displacement. I do not know how they were able to bore the block .100 over but that was the 409 combination that they built. Maybe they filled the block part way with block filler?
[Modified by bjankuski, 8:54 PM 12/6/2003]
[Modified by bjankuski, 8:55 PM 12/6/2003]
[Modified by bjankuski, 8:54 PM 12/6/2003]
[Modified by bjankuski, 8:55 PM 12/6/2003]
Drifting
Joined: Feb 2003
Posts: 1,978
Likes: 2
From: San Antonio Texas
Re: 409 C.I. LT-1 (Epyon127)
I don't think most 350s will take that much over-bore. Possibly an after-market, or GM performance block? Block filling is usually only up to the bottom of the water-pump holes at most, and is used to strenghten the block, keep the bores round, prevent ring flutter,crank-walk and such. I think if you filled the whole block, there would be no cooling.
:chevy
:chevy
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Mar 2001
Posts: 30,856
Likes: 293
From: Boston, Dallas, Detroit, SoCal, back to Boston MA
Re: 409 C.I. LT-1 (Vette92)
a 401 is done alot, stroke increase.
http://phil.tobin.net/Hoover/top.html
a 424 can be done, with a lot of work!
http://www.conversionxtras.com/1000hp.htm
http://phil.tobin.net/Hoover/top.html
a 424 can be done, with a lot of work!
http://www.conversionxtras.com/1000hp.htm
Drifting
Joined: Feb 2002
Posts: 1,952
Likes: 2
From: Little Rock Arkansas
Re: 409 C.I. LT-1 (BrianCunningham)
I'm in the middle of building a 415" LT1 right now for a friend's T/A... I swore I'd NEVER build a 350 based motor with a 4" stroke because of the clearance involved and the poor rod/stroke ratio... But here I am doing it anyway.
I've had to clearance the **** out of the block; so much that I wasn't comfortable milling as much out as I did so I put a short fill of Hard-Blok in the very bottom of the block for extra "insurance." Reduced base circle cams are a must to prevent rod contact with the lobes. The rod/stroke ratio is a poor 1.46:1 and I'm of the opinion that the piston velocity will be very high...
-Jeb
I've had to clearance the **** out of the block; so much that I wasn't comfortable milling as much out as I did so I put a short fill of Hard-Blok in the very bottom of the block for extra "insurance." Reduced base circle cams are a must to prevent rod contact with the lobes. The rod/stroke ratio is a poor 1.46:1 and I'm of the opinion that the piston velocity will be very high...
-Jeb
Melting Slicks
Joined: Apr 2002
Posts: 2,308
Likes: 1
From: Portsmouth VA
Re: 409 C.I. LT-1 (jburnett)
using the lunati pro-mod rods for my 409 with my 4" stroke didn't require nearly as much clearancing as i thought it might, and certainly not as much as what you guys sound like you had to do. i think they are great for the 4" stroke applications.
Drifting
Joined: Feb 2002
Posts: 1,952
Likes: 2
From: Little Rock Arkansas
Re: 409 C.I. LT-1 (SonnyinVA)
:D Sonny... Didn't you ask me to build a 409 for you awhile back?? And I told you "no way in hell" I wanted to do a 4" stroke in a 350 block?? And here I am building one anyway... :lol:
-Jeb
-Jeb
Intermediate
Joined: Jun 2003
Posts: 25
Likes: 0
From: Chaska MN
Re: 409 C.I. LT-1 (Epyon127)
Just to clear things up, it is a 4.100 x 3.875 motor. It is not a stock block, it is a GM race block that was available for the World Challange series. This has a lot more meat to be able to do the 4.100 bore.
Best to just do a 396, and leave room for a later re-bore to go to a 402. IMO.
Best to just do a 396, and leave room for a later re-bore to go to a 402. IMO.
Intermediate
Joined: Jun 2003
Posts: 25
Likes: 0
From: Chaska MN
Re: 409 C.I. LT-1 (Ramrod92)
Yes it looks like it would work. You don't have to clearance this block as much for the 3.875 stroke as you do with a stock block. So I am sure it will go.
The only problem is finding the block.
The only problem is finding the block.
Racer
Joined: Jun 2002
Posts: 428
Likes: 0
From: Dallas Tx
Re: 409 C.I. LT-1 (Terry@TPiS)
Is that block still available anywhere?
The only LT1/4 block I am aware of is the stock GM.
I'd love to see someone make a HD block with the LT configuration, maybe even in aluminum. A bore of 4.15 would be great.
The only LT1/4 block I am aware of is the stock GM.
I'd love to see someone make a HD block with the LT configuration, maybe even in aluminum. A bore of 4.15 would be great.
