I agree with Nic on almost everything car related. I get tired of being told everyone that doesn't put a china turbo on a junk yard truck motor and make 1500 hp is doing it wrong and just wasting money because we are beneath those that do.

I'm not building a **** box my car only has 33,000 miles on it and is super clean...well some people think GTO's are **** boxes even if brand new so there is that... in some cases they aren't wrong as it is a terrible chassis for drag racing. For some reason I like them enough to have bought a second one LOL.

I also like to go on long drives out playing around any time I feel like jumping in the car without worries. Just check fluids and start it up and go when ever I want... except this time of year when it's ice and around zero degrees out every day LOL

 

I haven't put one in a GTO but I don't see why not, it's supposed to have all of the standard locations for that stuff. We've run them in all sorts of Gen4 applications as it's basically the aluminum version of a GM LSX with some minor tweaks here and there.

 

You are asking questions on a public forum. Then get bent out of shape if the answers don’t follow your line of thinking instead of considering that your line of thinking *could* be wrong. A better power adder capable of your goal and more boost is the cheapest way to meet your goal. Which is what you asked about. That’s a fact. If you can’t see that, then you need to research more. There is no argument there. You just can't seem to admit it when you are wrong. Which is something you should work on.

The way you speak clearly shows you don’t understand the big picture. It’s all tied together. I answered the question with the ultimate power goal in mind that you gave. Point was… Fancy heads and big cubes are a luxury that is not needed if you are looking for the cheapest way to hit your power goal.

Prochargers do not have an IAT problem? What does that even mean? The blowers are rated at “X” Eff. at “Y” RPM. Thinking you are going to be efficient over speeding the unit is nonsense. It’s not at its highest Eff range where you have it now. Spinning it higher has quickly diminishing returns which is why it has a rated RPM in the first place. Adding an intercooler to an inefficient pump doesn’t fix the issue.

Do you know what your IAT temps really are without meth skewing the data? Pre/post IC pressure drops and temps?

 

LOL... you continue to speak in absolutes like your opinion is indisputable.

Where did I say I was looking for the cheapest way to meet my power goal? I didn't ever say that. I said I had a budget of roughly $25,000 over 2 years or in other words 12,500 or so for a short block and money for better heads and bigger head unit as well as fuel system a year later.

That doesn't equate to asking what is the cheapest way to make 1200+ rwhp at all.

I also said I wanted it to be reasonably reliable with the understanding that nothing is infallible, and it would require not having any fuel delivery or tuning issues.

I do not like turbos and yes, I know the pros of them on a street/strip car and there are many of them. I understand this and do not dispute that.

There are pro's to prochargers as well for what I desire. Being able to stage and leave off the foot brake barely bringing up rpm at all just above idle without building boost and bumping in. I absolutely hate that. I like the linearity of the procharger power delivery in relation to rpm. You don't value that, and I do. That is why when you state your opinion as facts and indisputable it shows your ego that no one could possibly have different goals and desires than you do. There are other reasons I prefer the procharger that you aren't willing to even consider since they are not your preferences, so I do not feel the need to discuss those any further.

I'm over spinning the procharger by 6000 rpm currently and my IAT barely ever gets over ambient during a pull or normal driving. The only time it climbs at all even on 90-100+ degree days is on a long drive with lots of stop and go while sitting in traffic for long periods of time. Then it drops immediately once I start moving again.

So, when you talk about prochargers having IAT issues when over spinning them your assumption doesn't reflect my personal experience with over spinning a modern procharger. This is with an air-to-air intercooler with an inefficient top end with untouched 241 heads. I did add meth to supplement my fuel system because the single magnafuel 4303 was struggling to keep up. I have a toggle to shut the meth off if I want to test without it. I ended up lowering my ethanol content to 50% so it's safe without the meth. I've tuned and made pulls with and without the meth via toggle switch to make sure I'm gaining a little with the meth but not going to hurt anything if the meth fails. Lots of people use meth fail safes, but I've actually tested mine to make sure it works. I saw no measurable difference in IAT with or without the meth and I'm only using a single small nozzle.

To be clear I absolutely have a budget, but I'm also willing to spend some money to have more cubic inches and more reliability. In a street toy I've found a few more cubic inches makes the car much more fun to drive around if it's a heavy true streetcar even if it doesn't make the car faster than a smaller engine with more boost at the drag strip.

 

I'd just wait and buy 6 bolt heads that flow well. Pricey.

 

What about cubic inches?

originally I was dead set on a 388. 4.125 x 3.622 now im thinking even with a dart, lsx, or lsr block I wouldn’t want to push the bore out that far to leave room for a rebuild.

Thoughts?

Maybe a 4.030 x 4 for a 408 or even stick with the stock stroke and do a 4.070 so it’s a 377 like my current 377 but with the stronger block.

 

Larger bore will unshroud the valves more in the head and opens up a lot more head choices as well. Especially with an aftermarket block I don't see any reason to go smaller than a 402 or even a 427. I'm running a 427 LSR setup in my C6 Z06 and it's been in the car since 2018 at this point without issue, and I'm not nice to it when I take the car out and beat on it.

 

No concerns with the 4” stroke with high boost due to piston height?

If not short block prices are the same regardless of cubic inches when using the same block and all forged internals. Might as well go 427.

 

Not at my power level which is ~1500 rwhp through a glide on a Dynojet, which is probably ~1800 horsepower or so at the crank. Just use good rods/pistons and it won't be an issue.

 

There is more war with a 4" crank (I've been told this repeatedly) but I think properly set up it's not that much more.

 

Many years ago, I had a 408 that I had to refresh due to hurting a piston with nitrous. All of the piston's skirts had excessive wear. I think this was from rocking as the piston was coming out of the hole at the bottom. I put alot of daily driver miles on that car as well as driving to and from 3 different drag strips racing every streetcar night at each of those tracks (3 times per month). I also put over 2 mother bottles of nitrous through the motor.

I'm more concerned with the compression height as the wrist pin on a 4" stroke intersects the oil ring where on a 3.9" or shorter stroke it does not. This in theory makes the ringlands stronger on a 3.9 or shorter stroke. Also more distance from the top of the piston to the first ring?

This may not be an issue at the power level I'm seeking 1200-1300 rwhp. I see the really crazy power LS combos lean towards a 388 for this reason like the guys pushing in the 2000 hp range.

 

Cylinder barrels are extended in aftermarket blocks to address the 4"+ stroke but piston CH is still definitely a discussion point. There are ALOT of 427 LSX/Dart LSN engines out in the wild at the level and much more. The question to be answered is, do they see legit street time and more than 100mi a year

 

Not an issue with aftermarket blocks as the block/liner extends down further than OEM specifically for the larger stroke.

Not an issue either at your or my power level. Even at 2000+ there are plenty at that power level without issue as the right pistons are plenty strong. I would say the bigger power guys are choosing the smaller cubes for block strength and sealing in addition to keeping turbos happier in their compressor map.

 

388 has become popular in the turbo world.

 

How much power are you wanting to make with them?

 

As previously mentioned easily over 1000 rwhp the first year and 1200-1250 rwhp eventually with this engine combo.

I already make around 1000 rwhp with the current stock block combo and 241’s.

 

Might help with your decision as we have very similar setups except M6 vs. A4 (rods/pistons 370, F1A-94, 230 cam, 9.5:1 CR, was FAST cathedral 102 now stock LS3 intake) . I picked up about 90HP and 80ft lbs going from ported 243's to ported aftermarket square ports from Smeding. Same timing, AFR, CR, and boost. I think the stock 243 2" valve and small ports hold it back under boost a bit. Of course if you are just looking to spread out your expenses, the shortblock first approach is probably a good one, that way you can sell the old SB before its a coffee table.

 

I’m definitely staying with cathedral ports but I’m planning to go with aftermarket castings.