Sorry to hjijack this thread, but I would love to have a debate on the statement that the LT heads are a weak link in the LT1 motor.
BTW, the head and chamber design IS the basis for Vortec heads and further "Fast Burn" tech.
Sure, porting WILL improve the flow. The same can be said about ALL cast heads.

 

What is the reason that the LT1 runs out of breath so quickly, especially in comparison to the LS1 motor?

That's a problem that LS1 guys don't have out of the box, and the major difference is in the flow of the heads.

 

You aren't seriously a COMPLETELY DIFFERENT MOTOR as the basis for your argument, are you?

If that's the case, dig up some old LS1 vs LT1 threads. Start around 1998.

 

Yeah, the LS1 has completely different powerband than the LT1. That doesn't mean the LT1 is "running out of breath."

 

You guys are entitled to your opinion as I am. I will stick to ported heads so my car can breath freely and not run out of steam at 5000 RPM.

There are guys with just cold air, exhaust and ported heads who are running 13.0 and slightly better.

If I'm going to do bolt on's to my LT1 you had better believe that I'm going to drop some money for a good port and polish because dollar for dollar it's tough to beat. $600 for a cold air intake and a cheap catback or pay somebody $600 to port my heads? It's a no brainer. The gains yielded from that are a testament.

And the LS1 is a different motor but it's still a small block chevy. Put a cylinder head on that engine that is as restricted as the LT1 cylinder head and that engine's power band is totally different.

Not using it as the only basis for the argument, but the fact remains that when the LS1 came out the cylinder head design was a huge improvement over the previous LT1 in regards to flow and powerband.

You guys want to stick with stock heads more power to you.

 

I'll add another vote for the LT1 heads NOT being the weak link. When you see a statement like "the flow is crap", I discount the entire post. Dwayne's italicized paragraph makes perfect sense to most of us.

 

With the engine in stock form, I'd say exhaust manifolds and cam are the weak link(as far as power goes). The stock exhaust manifolds are way restrictive and a good cam really wakes up the motor.

In stock form, my LT1 would hit a wall around 5100, but with my mods to date, I run out of breath around 6100.

Heads and fuel pump are next on my list to change. Given the path I'm taking to modding my LT1, I would agree that the stock heads were not my first concern to making more power.

 

Port the heads without exhaust and intake? Lol good luck with the ported heads and an engine that can't breathe. Best bang for the buck,gears,lt headers, and my personal favorite nitrous. 1400 bux and you'll have a very fast stock heads/cam lt1. All the mods go hand in hand. U don't build a 13to 1 383 stroker and run a tiny cam or stock exhaust. An lt1 likes air just like any sbc. Cold air intake on stock exhaust lt1 may make 5rwhp add in a set of lt headers and exhaust with u may make 35rwhp.you will definitely see a change in your powerband with the exhaust and headers.

 

Sorry for the double post but my car has heads that have been milled 20 thousandths and stock size manly race flow valves. Basically a stock head. I make 370 @ the wheels on a mustang dyno @6050 rpm at 2400 ft above sea level and 498 ft lbs of torque @3800 rpm.

 

You CAN'T be serious...?

 

But that was with a "150 shot" of nitrous according to your last thread. Introducing the issue of nitrous into a thread that is asking what the bottlenecks are in a stock engine is sort of pointless. He didn't ask how to add quick HP.

 

I'm not interested in Nitrous. Right now i'm thinking a cam with it's supporting changes such as rockers, springs and rods. I'm really not sure which cam as i'm new to the cam world - but it's will need to be street and emissions friendly. If i happen to find a really good deal on a set of heads - maybe i will consider them.

Would anyone know if it's worth going to a spun metallic cat? will it get me much more power?

 

Talk to Elliot. He can guide you to the strongest emissions friendly cam along with quality head work.
http://elliottsportworks.com/

 

The stock LT1 "runs out of breath" early because the valvesprings are weak, the fast bolton b-body cars with their smaller yet cam turn 5800 with spring and rocker upgrades.

This should be a lesson to the OP about how and who actually understands things.

So I guess we should say the stock spring are a weak link as they give up before the cam does.
B-body guys have documented float as early as 4800rpms with a first gear limiter of 5500rpm, but again like I said the fast bolton cars turn 5800 and some a little more with springs and rockers and the b-body cam is less duration and lift than the f-body.

 

That's a good point seeing as most people won't even run stock springs with 1.6 rockers. I think it's not commonly mentioned because it's usually assumed that the valve springs are upgraded with the cam swap to support the increased lift.