[laynlo15]

King I am using Water/Meth injection for additional fuel. I run the Aem 1000cc nozzle. I have the new Lt4 injectors ready to install and plan to do the low side lift pump before I start racing again in March.

[1LE801]

We just went full LT4 right from the jump to be safe after we had an LT1 let go around 620 wheel. We're adding twins in a few more weeks but I don't think we're going to even try the LT4 stuff alone. Sounds like the plan is to add LSA injectors and an aux pump. Wish it weren't necessary to do so.....

[laynlo15]

That's what Mike did from Magnuson, more injectors and big after market pump. I know I'll be pushing when I'm at about 725 on the stock LT1. If this one fails I'll build a big stroker and run down there in the low 9's. I'm gonna try to get a full season out of this motor and with my schedule this year I'll probably have at least 130 plus passes like last year and very few miles on the street again. I'm gonna limit my boost to about 15 lbs with my new setup.

[boostednut]

Originally Posted by laynlo15

That's what Mike did from Magnuson, more injectors and big after market pump. I know I'll be pushing when I'm at about 725 on the stock LT1. If this one fails I'll build a big stroker and run down there in the low 9's. I'm gonna try to get a full season out of this motor and with my schedule this year I'll probably have at least 130 plus passes like last year and very few miles on the street again. I'm gonna limit my boost to about 15 lbs with my new setup.

I'm fairly certain that lt1 failure is varied by the oem ring gap. I wish we could get guys to compression test stock long block lt1's. I'd be willing to bet with enough cars doing tests, we could get a decent distribution curve and we could tell which cars are tighter or looser.

If you have the money for a new block, just send that bitch! Let her eat

[boostednut]

Originally Posted by jessrayo

The limits of the LT1 engine are all very closely intertwined around 550 whp. GM developed this engine to make 450 hp and when you exceed that you run into multiple problems.

1. Fuel - you oversimplify with the LT4 pump and injectors. The car has both a low pressure side fuel system (electric in-tank pump) and a high pressure (mechanical) pump system. The biggest power boost can be gained by upgrading the low side pump. Not a lot of discussion about this because it is easy. Any of the pump upgrades from gen5 port injected cars can be used to supplement the low side.

High side upgrades are the main limiting factor in these engines. It is really hard to get the amount of fuel required to make big power through a tiny direct injector in a fraction of a second. High side upgrades currently can be done with a cam (increased lobe size gives more pump from mechanical pump), pump upgrade, or injector upgrade. Because the car uses direct injection these options are very limited. To this day very few aftermarket parts exist that are better than the stock GM parts and those that do exist are very expensive. Lingenfelter sells a 1000hp pump and injector set for $6000 and that is as far as I know the only direct injection system than can dyno 1000hp period. No other systems can touch this power level stand alone. The GM stock LT4 pump and injectors will give you around 800 hp max and it is really best to run them as a set. The injectors are designed to run a certain fuel pressure. The LT1 pump and injectors were developed along side each other and so were the LT4 parts. You can run the LT4 injectors on the LT1 pump but they are not as efficient and same with the LT4 pump with LT1 injectors.

Perhaps the easiest way to overcome this direct injection fuel restriction is to add a port injection system on top of the direct system. This is exactly what GM did to get the power they wanted from the new ZR1 corvette engine. Many builders have done this to make big power builds but so far the factory computer does not support this and the aftermarket is a cluster of not well tested products. There is no doubt in my mind this is the direction we are heading to beat the limits of direct injection but the tech is still relatively new.

2. Compression - The stock LT1 is 11.5 to 1 compression. Boost has a multiplication effect on the compression ratio of an engine and when you add a forced induction system you are very limited in the boost you can give the engine before the fuel is so compressed you get detonation. If you run alcohol this not an issue but most of the fuel sold in the USA is less than 10% alcohol. In reality that means unless you are making specialty purchases of fuel like E85 or race gas the LT1 engine is only going to safely make about 650 whp on a tune where you could drive the car across the country and buy gas at the pump.

3. Piston and ring design - the LT1 was not designed to run boost and many, many people that have boosted the LT1 engine over 600whp have experienced an engine failure related to pistons, rings or even rods. To be honest the previous GM LS pistons and rings were better able to handle boost than these new LT1 engines. The stock LT1 engine really needs a piston and ring upgrade if you plan to take the engine over 600 whp and run it hard.

In my opinion the LT1 is about a 600 whp max engine without major upgrades. The LT4 is about a 1000whp engine without major upgrades because GM adjusted the compression ratio and piston and ring problems. So, not just the LT1 injectors or mechanical pump but a cluster of limitations.

I appreciate your post. I'm sure a lot of people will learn from this, but this is far from my first venture with a boosted engine.

High compression puts the limit on your fueling, not the piston. You can run fat or higher octane to get around this.

I don't think "600whp" is the limit. Since we want to talk about over simplifying the limit is posed by ignition timing and fuel, as it's been well documented that lt1 pistons are the issue. It's also been suggested that the ring gap is inconsistent from GM. We can't put a "limit" on this part until we've established that 600whp is not a functional number.

First because dyno numbers are a joke. The only realistically accurate way to compare power is trap speed with similar DA, similar weight and similar drive train. Otherwise it's a crapshoot. A dyno is a tuning tool. Not a ruler to measure your dick with.

Next power delivery is different for power adder. Roots have a lot more load low end that can change in combustion chamber conditions on a long pull, compared to even just a centrifugal blower. The increase in torque of a roots blower will also mean much more rod load as well. But more grand scheme, you can't compare "600whp" from a big 2.9 whipple to "600whp" to that of a turbo, na, or even nitrous. Parasitic loss is different for each, meaning that the piston and rod loads experienced in each are different.

Then that means even more for fuel system. Blower cars need more injector and pump than non blower cars. Cam timing is different for each, which means valve overlap is different for each, meaning dynamic compression is different for each. Which means different combustion chamber temps across the strokes.

Lastly the lt1 has been pretty well proven on the c7. Yes the load is lower on the c7 due to less weight, but I think a lot of people are being steered shy of the lt1's actual functional potential from a few bad experiences. It might be that GM uses less consistent tolerances on the SS than the c7, but without further probing we can't say for sure.

Again, I appreciate your post. I'm sure a lot of people will learn something for it. We can take tangents all day. Down the road I'm sure plenty of people will google and find these posts and learn something new. But I created this thread to try to answer a specific question, that personally the last 6 months of reading have yet to shed any direct light. Your post, and this may come across harsh, however well intended puts us nowhere closer to an answer of the topic at hand.

[boostednut]

Originally Posted by 1LE801

We just went full LT4 right from the jump to be safe after we had an LT1 let go around 620 wheel. We're adding twins in a few more weeks but I don't think we're going to even try the LT4 stuff alone. Sounds like the plan is to add LSA injectors and an aux pump. Wish it weren't necessary to do so.....

A buddy of mine jokingly said I should just get a wet shot controller and spray fuel in that way. I mean he's right... It would get more fuel in.

I've noticed a lot of GM guys just use a single nozzle meth system. I think direct port is a great solution... And I'd be willing to bet if you found the right stainless lines you could just use straight ethanol instead of meth. With a nice controller like an ALKY control one controlling a fuel pump in a mini tank in the rear, you could just do that instead of using injectors. Throw in some check valves on each port, with a fail safe device on the main line to check for leaks/blocks/flow. Even with top shelf parts it would be probably half of what some of these shops want for their AUX systems.

If you were real clever you could check for fuel pooling on the dyno, with a bunch of different methods.

[parish8]

I am stock from my the heads to my 20" rims. I have a ton of runs at 700+rwhp(dyno jet). 113mph in the 1/8th, full weight. i also have an extensive fuel system, run e85 and have never floored it for more than 11sec. maybe i got larger ring gaps from the factory or maybe running plenty of good fuel and not flooring it for longer than a 1/4 mile is all it takes to keep these things alive.

[parish8]

Originally Posted by boostednut

A buddy of mine jokingly said I should just get a wet shot controller and spray fuel in that way. I mean he's right... It would get more fuel in.

I've noticed a lot of GM guys just use a single nozzle meth system. I think direct port is a great solution... And I'd be willing to bet if you found the right stainless lines you could just use straight ethanol instead of meth. With a nice controller like an ALKY control one controlling a fuel pump in a mini tank in the rear, you could just do that instead of using injectors. Throw in some check valves on each port, with a fail safe device on the main line to check for leaks/blocks/flow. Even with top shelf parts it would be probably half of what some of these shops want for their AUX systems.

If you were real clever you could check for fuel pooling on the dyno, with a bunch of different methods.

ethanol is less corrosive than methanol. you can run strait meth or ethanol with most kits but they have to be careful with what they say since meth is flammable if mixed over 50/50 with water. methanol is the better fuel to run if your going that route, many of the crazy fast no prep cars are switching over from ethanol to methanol.

i think an all out port meth kit would be a great way to go. in my mind a decent shot of port meth combined with premium through the direct injectors would go a long ways. i did the port fuel injection partly because the add on ecm comes with a pile of other cool features like boost control, nitrous control, fuel pump control, 2 step, logging of multiple extra inputs........ also i just have one tank to fill which is nice.

[laynlo15]

I have 130 plus 1/4 mile runs last year on mine. Lots of dyno pulls also. Still together at 670 rwhp. I have a very simple fuel system compared to Parish, little less hp right now but more coming this month when I do the lt4 injectors and smaller pulley.

[Drsagacity]

Originally Posted by laynlo15

Parish I might have someone interested in the pump. I'll get hold of him and let him know you have it.

Am I that someone?

[laynlo15]

Russ, that was another buddy of mine that bought his pump and he already was working on a fuel system when Parish made the comment his was for sale.

[Dysan911]

so after reading everything in this thread. Would you guys agree that FUEL is probably one of the biggest and smartest things to do to an FI car as far as engine longevity is concerned? I know it's probably not the "ONLY" thing but a huge factor right?

I'm planning to up the boost a little but before that going to do the full ZL1/LT4 fuel upgrades. Intank FP, HPFP, injectors, etc.

[JANNETTYRACING]

Originally Posted by Dysan911

so after reading everything in this thread. Would you guys agree that FUEL is probably one of the biggest and smartest things to do to an FI car as far as engine longevity is concerned? I know it's probably not the "ONLY" thing but a huge factor right?

I'm planning to up the boost a little but before that going to do the full ZL1/LT4 fuel upgrades. Intank FP, HPFP, injectors, etc.

Absolutely, you can't make power without fuel and the safety of the engine relies on having adequate fuel supply..

Once fuel delivery is conquered, the next hurtle is the Octane wall.

We can only put so much boost pressure on the octane available in your area.

When I drive my 700 HP ZL-1 I put 93 octane pump gas in it.

When I race it on the road coarse I puts 100 octane unleaded in it.

Ted.

[Dysan911]

Originally Posted by JANNETTYRACING

Absolutely, you can't make power without fuel and the safety of the engine relies on having adequate fuel supply..

Once fuel delivery is conquered, the next hurtle is the Octane wall.

We can only put so much boost pressure on the octane available in your area.

When I drive my 700 HP ZL-1 I put 93 octane pump gas in it.

When I race it on the road coarse I puts 100 octane unleaded in it.

Ted.

THanks Ted. I am well on my way now to conquering my fuel!. Just completed ordering all the fuel goodies.