Let's Build Another Turbo Engine!
 

Ladies and Gentlemen, Boys and Girls of all ages, I am getting ready to build another LS (that hopefully won't explode) and I need some input.

The Car:
87 Foxbody 3050lbs with driver
T56 Magnum XL
Biilet 8475 T4 turbo
NON-INTERCOOLED
Methanol injection Pre-turbo (from my pump+meth days)
Ignite Red 114 (E90) fuel
100 shot of Nitrous on a scamble button

I do a lot of 1/4 mile stick shift racing and a fair amount of no prep/no time 1/8 mile stuff as well. This is a street car too. It will get around 1000 street miles on it a year.

Goals:
1000 hp or (close to it) tire
High 8 seconds, 150+ mph trap

Budget:
Stay budget friendly in recommendations, I don't want to dump a bunch of money into a new motor, but I'm willing to pay enough to meet my goal.

Current Build Sheet:
Brand new GM 5.3 Iron Block -owned
Stock Crank -owned
ARP Main Studs -owned
Summit Forged Pistons/Rings/Rods
Wiesco Tool Steel Wrist Pins
Clevite Bearings
Summit SFI Balancer with ARP Bolt
Melling Oil pump -owned
Billet timing set -owned
BTR Stage 2 turbo cam -owned
LS7 lifters in LS2 trays -owned
Chromoly Pushrods
Trunion Upgraded Rockers
LS9 Headgaskets
ARP Headstuds -owned
BTR .660" Dual Valvesprings -owned
Front/rear covers
Other Gaskets
Coils/plug wires -owned
Water pump/manual belt tensioner -owned
Machine shop work

I own some of this, some I need to buy.

Now to get more specific:
1. In my current SBE setup, I continue to break ringlands on cylinders 5 and 7. No detonation, just hot IAT's (mid 200's). What ring gap should I run? Blow-By does not bother me, I just don't want to break ringlands anymore. I'm going to relocate the turbo inlet in the engine bay this winter and it should help drop the IAT significantly.

Main Question:
2. I would like to run as little boost as possible to reach my goals (20 psi or less would be nice). If I put a set of decked 862 heads on it (58cc chambers), that would give me a CR of 11.0:1. I have a set of decked 317 heads (67cc chambers) which would give me a 9.4:1 CR. Is the extra CR worth it? Also, say I ran a Cometic headgasket with a thickness of .040 vs the LS9 of .054, that should take it up to around 11.5:1. I'm not well versed on compression ratios and their effect so looking for some input here. Remember, I want to run 8's with under 20 lbs of boost. And say I do go with the high compression route, are the parts in my rotating assembly going to hold?

3. I haven't installed the nitrous kit yet, but it would be a very easy way to get out of the hole quickly (stick car so no transbrake) and have a scamble button if needed.

Closing thoughts:
I am not dead set on anything in this post and I know there is a ton of information to be learned on this forum, so please, show me how to make horsepower! Am I on the right track or would you do it differently? Let's hear it!

I'd forgo the spray and just run a 2 step to build boost off the line.

Seems like between the high octane and meth you should be able to run the higher compression route. 11:1 sounds good.

@Summitracing should be able to comment on the limits of their pistons/rods.

I've never understood the "I want to run as little boost as possible" ideology. You aren't doing yourself any favors. Keep it simple, pour on the boost.
Make sure that you have a good fuel pressure regulator with a boost reference and that you are able to keep intercooler piping sealed up.

A higher static compression ratio will put more stress on the engine than a higher peak boost will in most circumstances,
and you're spending extra money and going through extra precautions to do it with almost no benefits over more peak boost.

We'd have a tendency to keep C.R. in the mid 9:1 range even with your excellent fuel an the Meth beyond that. It's going to open up your tuning window...and as Joe has remarked, you can always run more boost. If you're running 1000 street miles a year, it won't always be on Ignite and you will have to latitude to run a mix with the lower C.R.

You are an onward and upward sort of guy, so the toolsteel pins are a solid decision past 1000whp or with a 300 shot of nitrous. You're going to eclipse that with that turbo and a 100 hit...so good idea to move up to the better pin....they'll be with you for a long time.

Our top rings are down .275 on the 5.3's and .300 down on the 5.7's and larger. That shields the rings from heat, so you'll find a .024 top and .026 will be fine on the gaps. Ring land breakage from pure power is rare and we've got the thickest lands and the valve reliefs are built to maximize strength in this key area. If it was a stock piston or Hyper, you'd have to run more than that.

I'm also going to guess that this is the On3 8475, which hasn't ever been proven to make the numbers you're after. With the smaller .96 A/R T4 turbine and 3" outlet, I'd be surprised if it was even capable of those numbers. Maybe your 6 speed will help.

Spray on a T4 75mm turbine... not sure if serious? Two step will make ALL the power you need to leave on and more. I would forgo the 8475, if you want a cheap similar turbo get the Gen2 7875 it'll work better all around.

No need for ignite either, regular pump E85 is more then sufficient for your goals. In fact I would scrap all that overpriced fuel, nitrous, meth, etc and just add an intercooler and run straight E85, be an overall cheaper setup that works just as well if not better, be more reliable and be more consistent.

I bet your broken ringlands will go away if you just add an intercooler, sounds like you have too much timing in it for the 200+ IAT's.

bigass intercooler + e85 = happy brappy fun times

My intercooler sucks for whats being forced through it and I'm still able to run well over 20 lbs with cheap local E85 on a stock gen 3 short block.

I agree with the above, you are corking up the engine with a T4 and smallish Exh wheel. That’s a bad idea in general… no IC on top of that is even worse… and limiting boost is ridiculous.

Nothing wrong with running NO IC, but the point (or at least one point) for running No IC is you can go larger on the turbo with less lag. Zero reason for a T4 on any LS IMO. They are all a bottle neck, esp at 1000hp. With a 100 hp shot you won’t have any trouble spooling a much larger turbo. Personally I’d go with the On3 “pro-mod” style 91mm with the 103mm Exh wheel. The cast unit is pretty darn affordable. I wanna say $950? Anyway non intercooled setup will need to run more boost than intercooled setups to make the same power. So really shooting yourself in the foot there. Small engines need more boost and RPM than a larger one. That’s not a bad thing.


I’ll also say you’re going through a lot of machine work and BS. For your goals and “budget friendliness” Source your self out a Gen4 SBE alum engine and be done with it. It will drop about 80lbs off the nose and will handle your power goals if tuned correctly.


I’m basically doing what your wanting on a “cam only” $500 SBE 4.8. T6 china S480 combo (intercooled on E70) at a very similar race weight around 22lbs with a glide. Using the much cheaper ARP bolt instead of studs as swell. (ls9 gaskets) You don’t need 1000WHp to run 8’s at 150+ at your weight either. Guessing I’m a bit under 900 and trapping 156. And honestly that’s nothing these days. Lots have been faster on 4.8’s…even more so on the 5.3’s.


Why not run an intercooler? They are cheap…and will give your more power per pound. Little A2W unit works great if you don’t have the space up front. You don’t even need to ice them. I run .022-.024 gaps on my small bore stuff and I’ve never butted a ring. I’d say your tune is questionable if you are having issues there. (and I’ve used a 70ish shot to get the turbo going without ring issues as well) Keep compression down to make tuning easy. No need for higher compression and lower boost that’s counter productive as mentioned…makes no sense.


IMO Use the nitrous to get off the line and shut it off. You’ll have to flat shift to keep boost up between shifts. The manual trans makes your goals much more difficult. It’s a cake walk with an auto…though I respect you for sticking with the manual… they are fun…if they live!

Ya for a goal of 20lbs (hell even 25) and a weight of 3,050lbs, pretty much the last thing I would be doing is building an engine.

I think the last place he needs nitrous is off the line, the car should be able to pull a 1.2-1.3 60' really easily off the two step and a few lbs of boost. A 5.3 will spool a 91 without nitrous easily enough, almost too easily if tune is right, plan for boost by gear. But like you said he doesn't need 1000hp+nitrous to get there, more like 750-800hp to run high 8's at 150+ at that weight. Spec'ing a promod 91 for 750hp with a manual trans wouldn't be my first pick, but at least he wouldn't need to upgrade if his goals change and he wants to make 1300 instead and run 7's. That said multiple T4's have recently put down 900+whp on 5.3's and spool up extremely fast. The Gen2 7875 put down 900+ through an auto on fairly low boost, so it'll get the job done with a manual pretty easily.

Totally agree on the Gen4 aluminum, beasts! But he already has the iron, can use it, shake the car down and keep an eye out for an aluminum and swap it later once the car is sorted and bring it under 3000lbs.

That high IAT isn't going to help your cause to reach your HP goal. Get it to 150* and gain power and tuning benefits. What is your max rpm target? With the thicker piston crown you're surely safer to avoid ring butting and popping lands.

Curious what WHP with e85/e90 summit has seen with ring gaps at .024". Any sign of shiny rings ends showing contact?

Wow, thank you all for the responses and lets keep this going because I want to do it right. So basically scrap the nitrous idea, no big deal. I have a two-step, but it takes a second to build boost, but I haven't played with timing on the two-step much so I can probably figure that out.

For my current timing table, I am running 19 lbs of boost at 9 degrees of timing (verified timing). Granted, my IAT's were in the low 200's, CR at 9.4:1, but I feel like that was very conservative, yet it still broke ringlands with a .026 top ring and .028 bottom ring gap. This is the issue I am trying to get away from by building a new motor (and make more power).

In terms of my hp goal of 1000 tire, that is not a "must have." I want to run high 8's. That's my goal. I would agree with others that it won't take 1000 tire hp to do it. More like 800 to 850 tire.

Let's dive a little deeper.

I currently have an aluminum L33 gen 4 SBE in the car. Cylinder #7 will need cleaned up due to a ring land digging into the cylinder. I was going to sell it as is because I didn't want to bore/hone out the aluminum block to the point it was too weak. I can barely catch my fingernail on the scratch, can I safely bore it out and still use it for boost? Or do I just run the iron block I already have ready to go? It currently weighs 2940lbs with driver, full of fuel. The 3050lbs would be adding the weight of the iron block. I am not concerned with the extra weight of the iron block, I still have a stock k member in the car so I can drop another 60 lbs off the front end by upgrading that.

I'll listen to you guys and do a mid 9 CR and pour in the boost. I need to remember these motor's love boost and I need to give it what it wants. And since I do my own tuning, it will give me some more lee-way if the tune isn't perfect.

As far as the turbo goes, I'd like to keep this one. Surely, it can make 850 tire with my setup if I push it into the upper 20's and if that's how much power it will take to run an 8, I don't think I should go spend money on a new one. If I get the motor together and I max out the turbo and it can't go 8's, I'll upgrade it. ( I'm not saying a better turbo wouldn't make it easier).

As far as my engine components go, am I on the right track? Forged Pistons, Forged Rods, Tool steel pins, Stock Crank. Should I skip the Forged Rods and Tool Steel Pins?

I resisted switching from pump e85 for a long time until a friend blew up a motor on pump e85 and had the fuel tested, it had a fair amount of kerosene in it. I also know a guy with a 540 twin turbo BBF that switched from e85 to Ignite 114 and picked up 120 tire hp on the fuel change (and the tuning it allowed) only with dyno charts to show. I can drive 20 mins to Ignite and buy a drum of it for $300. That money is well spent in my mind.

Lastly, in terms of machine work, that just means a hone for the new pistons, and balance the crank.

I greatly appreciate the input guys. I know if I went with a bigger turbo, big intercooler, swapped in an auto, went back to e85, etc etc, I can make more power, go faster, and do it cheaper than what I want to do, but I already have a lot of money invested in what I have, I'm just trying to go 8's lol.

If it doesnt clean up with a hone, you can certainly bore it to 3.80 and still run plenty of boost. I've run BTR Wiseco 3.80 boost pistons at well over 30 PSI without issue. But if you could clean it up and throw another stock piston in it I would go that route first.

$5.45 a gallon is still over double what E85 is at the pump, for you at low mileage it may make sense. But for as much as I drive my car it would add up quick! I'm guessing they had some aggressive tunes if they blewup with small changes to E content.

How did the plugs look on 9* at that temp? I tried no intercooler and also couldn't get timing worth a shit in it with super high IAT's with a tad lower compression, I added an intercooler and picked up 15+MPH. A cheap treadstone intercooler too, nothing fancy.

Ewww never go auto! If you can get that car down to 2,900 fairly easily its gonna be a fun damn ride! I would do the K member which more then double offsets an intercooler weight.

Also, I am going to make an intake pipe for the turbo over the winter. It is currently sucking in air from under the hood and right behind the radiator (obviously the worst spot possible). Just idling/cruising it is taking in 130* air, that's where the mid 200* IAT's were coming from I believe. I'm going to route the new intake pipe in front of everything so it should be getting as close to ambient air as possible. I threw this last motor and turbo setup in in less than a week to make it to a no-prep race I wanted to go to all year so the intake pipe didn't get made in time. If I can drop the initial IAT's from 130* to at least 90*, that will keep IAT through the majority of the pull in that 150 range and at the end of the pull under 200*.

19 PSI, 9 degrees of timing? What fuel is this one? Timing too low can cause ring land failure too.
I ran 24-26 PSI on the regular on my stock L33, 12 degrees of timing, pump gas and meth. Zero issues. No detonation.
My corvette makes 9-10 PSI on wastegate, 20 degrees of timing, on E85 with a crap intercooler.
Surprisingly, I'm still running 17 degrees peak timing at 20+ PSI on a stock gen 3 4.8 and it has zero signs of any issues.

Skip the nitrous. It should be an afterthought kept just for launching. Don't even think about it unless you get to that point.

The aluminum 5.3 blocks can be bored out to LS1 spec.

That turbo isn't exactly a popular one for a lot of reasons. Very mismatched compressor/turbine.
It could probably make the power you need to go 8s, but when you have that small of a turbine, camshaft selection and downpipe/exhaust design play much bigger role than normal.
You could go 8s on your setup with an S480 with any of about 250 aftermarket camshafts. That 8475 will narrow it down a lot further.

Knowing my buddy, that motor was set on kill!

Humm... maybe I should have my shop look at my L33 and see what they say. I talked to a few race shops in the area and they were leery about boring an aluminum block, but they also don't have a bunch of turbo ls experience. I live in a nitrous SBC/BBC or circle track SBC area.

The plugs looked great, just looking at the plugs, I would have added more timing.

And I suppose i"ll look at intercoolers...

Again, should I just run the stock rods? I'm definitely going to go forged pistons, but are forged rods, tool steel pins necessary?

Why no intercooler? Ask yourself, how many guys running 8's without M1 and no intercooler?

At your power level Gen4 rods are not the weak point. Really neither are the pistons unless you have to replace them due to engine bore.

I honestly don't think the 8475 can hurt a Gen 4 engine, I ran one as well as the 8884 pretty hard without issues.

This setup I ran on both e85 and Ignite e90, broke ring lands on both fuels.

I am running a BTR stage 2 turbo cam, turbo headers with 1.75" tubes, 2" from the header collector to the Y pipe that is just under the turbo, 2.5" pipe out of the Y into turbo flange, 5" downpipe 3 feet long then out the fender.

You are totally right about my turbo, and I know its not the ideal turbo. All the parts I'm using are parts that nobody wanted and sold to me cheap. Now I'm using their old crap and gapping them on the street with a 6 speed. Everything about this setup should make it slow, but I take a lot of pride in it! Now I'm just trying to keep my car faster than theirs and if I can continue to beat them with their junk, I will lol.

JoeNova, would you bore an L33 or use a stock bore LM7?