[Slowhawk]

Blocks can handle a lot. Stock rotating assembly depends on how lucky you are. I've seen pistons crack in 1/2 at only 600rwhp, then some motors taking 700-750 no problem.
In 2014 there was a lot of problems on piston quality. It seems that the quality got better as the years progressed.

[toohighpsi]

I'm running 730-750 RWHP with Maggie on a completely stock engine - valve covers have never been removed.

Just drove the car for the 1400+ miles of Hot Rod Power Tour - we ran it in the autocross and drag events on the tour. While it was hot, humid, and track prep was non existent, my fastest ET on the Tour was 10.18 and my slowest was 10.4. As long as you don't run it out of fuel or into any knock, I'm pretty confident that all of the stock parts are good for 1K flywheel HP (900 RWHP). See you at the track!

[DenverTaco07]

Originally Posted by toohighpsi

I'm running 730-750 RWHP with Maggie on a completely stock engine - valve covers have never been removed.

Just drove the car for the 1400+ miles of Hot Rod Power Tour - we ran it in the autocross and drag events on the tour. While it was hot, humid, and track prep was non existent, my fastest ET on the Tour was 10.18 and my slowest was 10.4. As long as you don't run it out of fuel or into any knock, I'm pretty confident that all of the stock parts are good for 1K flywheel HP (900 RWHP). See you at the track!

can you explain what tuners will do to the tune in order to reduce chance of knock?

[mjmenke]

Originally Posted by DenverTaco07

can you explain what tuners will do to the tune in order to reduce chance of knock?

Quick and basic answer...They will run less timing and add more fuel (make it run rich).

[DenverTaco07]

Originally Posted by mjmenke

Quick and basic answer...They will run less timing and add more fuel (make it run rich).

Thank you, I will research the implications of pulling timing - I'm a total noob so...

[jessrayo]

Well since I put in my 2 cents earlier I'm going to have to retract my earlier statement about no problems with 650whp. I took my car to eagles canyon raceway on Saturday and broke the ring-lands on one piston. Ambient temps were close to 90 and the car had been going full out for about 20 minutes when it let go. Still runs but blew oil out the front main seal and shows one dead cylinder on the diagnosis. I do know that road courses with longer straights are a lot more taxing on your engine than 1/4 miles so I guess it depends on what you plan on doing with the car. I'm looking at replacing the pistons for sure now, don't have a choice.

Just a side note I was mixing race and pump gas so I'm estimating I was about 95 octane and didn't have any knock at all. It was very strong and I was reeling in some very fast cars in the advanced group before it let go. Never ran out of methanol so I'm confident afr's remained optimal. I'm pretty bummed because I wasn't planning on footing this bill but stuff happens. Now I'm thinking if you road race in hot weather you need to limit the stock block to about 600whp or less.

[Turbo_RORO]

Sorry to hear about the piston failure. Jessrayo PM sent.

[toohighpsi]

Originally Posted by DenverTaco07

can you explain what tuners will do to the tune in order to reduce chance of knock?

Only things you can do are:

1. Manage inlet temps - improve intercooler performance and/or water injection.
2. Increase fuel octane.

Boosting on an LT1 engine is balance of IAT, octane, boost, and timing. These engine do not like to be rich, anything richer than 11.8 - 12.0 A/F ratio does not seem to have any particular benefit to controlling knock (but richer mixtures do help control catalyst temp).
As with any engine there is a balance between these to create the highest power - and it normally doesn't end with more boost.

I see lots of people looking to upgrade their fuel system, if you're running pump gas without water injection and/or higher octane fuel there isn't really much to gain. These boosted 11.5:1 compression ratio engines will run into the knock limit on pump gas long before they run out of fuel when tuned properly.

If knock is controlled, the fuel system modification become beneficial and you can push the engines pretty hard. Last week in Indy it was about 90 degrees out - I was running MS109 unleaded, ~1600cc/min of 50/50 water/methanol mix, and about 16psi of boost with the maggie to low 10s at 135+ MPH. After the first pass it was clear that I had plenty of capacity in the fuel system and was wishing that I had went with a 70% water / 30% methanol mixture for better cooling. I started with the 50/50 to be on the safe side with fuel.

Fuel system currently on the car is LT4 injectors, Big Bore HPDI pump, and ZL1 in tank. I was running a 12.5:1 A/F ratio with about 25 degrees of timing and 16 psi of boost - please don't try this at home

Link to one of the 10.4 passes below, I'll get the 10.18 pass posted shortly.

https://youtu.be/rgcxshhUKOs

[PinHead]

Originally Posted by toohighpsi

Only things you can do are:

1. Manage inlet temps - improve intercooler performance and/or water injection.
2. Increase fuel octane.

Don't you also modify the timing curve when changing the tune to address knock?

[DenverTaco07]

Originally Posted by jessrayo

Well since I put in my 2 cents earlier I'm going to have to retract my earlier statement about no problems with 650whp. I took my car to eagles canyon raceway on Saturday and broke the ring-lands on one piston. Ambient temps were close to 90 and the car had been going full out for about 20 minutes when it let go. Still runs but blew oil out the front main seal and shows one dead cylinder on the diagnosis. I do know that road courses with longer straights are a lot more taxing on your engine than 1/4 miles so I guess it depends on what you plan on doing with the car. I'm looking at replacing the pistons for sure now, don't have a choice.

Just a side note I was mixing race and pump gas so I'm estimating I was about 95 octane and didn't have any knock at all. It was very strong and I was reeling in some very fast cars in the advanced group before it let go. Never ran out of methanol so I'm confident afr's remained optimal. I'm pretty bummed because I wasn't planning on footing this bill but stuff happens. Now I'm thinking if you road race in hot weather you need to limit the stock block to about 600whp or less.

oh man...that sucks.

Let us know what you end up putting in. If I get further itches to increase HP i'll be looking at short block work for sure. Would be nice to have a few "kits" available.

[jessrayo]

Originally Posted by DenverTaco07

oh man...that sucks.

Let us know what you end up putting in. If I get further itches to increase HP i'll be looking at short block work for sure. Would be nice to have a few "kits" available.

I'm trying to decide how far to go while I have the engine out. At the very least I'm going to drop the compression ration to 10 to 1 so I can run a little more boost on pump gas. I'm serious thinking about going up to 416 cubic inches with a stroker crank just to improve air flow a little into the turbos and improve torque before it comes into boost. I will definitely put in a new cam with the bigger fuel lobes. Then when everything is off why not port the heads....upgrade the valves.....put in a higher rpm valvetrain.....upgrade the oil pump..... why did this thing have to break? I just can't bring myself to doing a "cheap" rebuild....

[Joe's_cool_1le]

Not necessarily off topic but i'm considering how much HP during my travels I'm now looking at this.
https://www.texas-speed.com/p-4412-t...ort-block.aspx

[DenverTaco07]

Originally Posted by jessrayo

I'm trying to decide how far to go while I have the engine out. At the very least I'm going to drop the compression ration to 10 to 1 so I can run a little more boost on pump gas. I'm serious thinking about going up to 416 cubic inches with a stroker crank just to improve air flow a little into the turbos and improve torque before it comes into boost. I will definitely put in a new cam with the bigger fuel lobes. Then when everything is off why not port the heads....upgrade the valves.....put in a higher rpm valvetrain.....upgrade the oil pump..... why did this thing have to break? I just can't bring myself to doing a "cheap" rebuild....

yup, go all out at this point. I'm thinking if my motor goes, may as well go balls to the wall.

[EDFHOBBIES]

Originally Posted by jessrayo

My car has seen over 7000 miles over 650whp. I owned it less than a week before it got turbos. The internals are all stock. I don't daily drive it, it is a toy. When it leaves the garage I usually run it hard. No problems yet. If you stay below 700whp the stock motor should be fine.

Are you running meth and cam w a different fuel lobe profile?