Hi - I have a 2005 Vauxhall Monaro LS2 6.0 litre manual trans (basically a Pontiac GTO)

The plan is to go forged rods and pistons and add twin turbos. Contenders are Borg Warner S366 or S363. Either will make more power than a street car really needs but I need some advice on an all round package.

Compressors are obviously 66mm and 63mm. However the S366 has a larger 80mm turbine and the S363 has a smaller 76mm turbine - both through an open 0.88AR. Spool wise the S363 should have the edge BUT realistically how much of an edge would that be? On this size turbo would a 4mm difference in turbine size actually be perceptible on the street? Does anyone have comparable back to back experience of the two?

I have enclosed compressor maps for both with max boost of 16psi and a 6800rpm redline. Both look like a good fit with the S366 perhaps just marginally better overall in terms of island efficiency.

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My next question is about the actual packaging of the S366 against theS363. Obviously space is tight under the hood so a smaller turbo footprint is always better. Although both turbos have the same frame the S366 is of a traditional layout like a Holset HX40. The S363 has a weird 90 degree elbow coming out of the compressor and a sort of elongated turbine housing where the V-band fits. This could be a real compromise in terms of space. Thus, my question regarding 'is the spool difference worth it' acts as a compromise against the more unwieldy packaging of the S363 in terms of going with the slightly smaller turbine. What do you guys think? I only have photos for reference, so does anyone have hands on experience of the packaging differences? Is it really an issue or am I finding a problem that isn't really there?

S366

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S363
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Final question - compression ratio to be set with the new forged pistons. Bear in mind the boost limit will be 16psi, so I was thinking something in the region of 9:1 - 9.2:1 as a safe tune option. Sure it'll lose a little response in terms of it being low BUT could this be compensated for in the tune by running comparably higher timing than you would with a higher CR? Any input here would be gratefully received.

Thank you for time.

Adam (from rainy England).

 

The 366 is better in efficiency that's the one I'd go with for a twin setup the temps will be a little lower plus a better efficiency . Did you ever consider doing a single turbo? Like a 7675 ?It's a little easier to fit a single turbo smaller engine bay especially if you dump the exhaust out the fender. 9.1-9.2 cr will be fine for boost. If you up your octane with e85 or race gas you can run a little more timing or add a tiny bit more boost as long as the engine will handle it.

 

Thanks for the reply. I did consider a single but the cross-over and then splitting a single turbine outlet into an existing £1,200 twin stainless exhaust (which I wanted to keep) would be a plumbing nightmare. Probably more simple to do one turbo per bank and drop them into the existing exhaust.

Unfortunately here in the UK we've not caught on to E85 yet. The best available fuel we have is 100RON which uses a different system than the US so it's hard to draw comparisons. We'll just have to be careful with the tune. There's really no need to max out the tune on a pair of S366's for a street car. We're not permitted to use slicks because it rains most of the time here... so tire traction is the usual power limiter. I guess it saves broken engine and drivetrain parts over the long term. LOL.

Any other comments or feedback guys?

 

As long as your careful with your tuning like you said you'll be fine. Are you gonna run an intercooler and or meth inj to keep the iat down? You should be around 800 flywheel horsepower with 16psi.

 

Yes, large intercooler for sure in the initial build. May add some meth injection later for octane / safety.

In terms of numbers I've inputted the tables below. I've used 'peak settings' based upon max 80mm / 0.88 turbine flow without choke which is max boost of 18psi. In truth I'll probably limit it to 16psi so as not to be on the limit, which will drop the bhp / torque figures a little. What do you think?

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Further comments and advice welcome...

 

If you want more room to grow the s369 turbos might be a better choice . https://goo.gl/images/UqKsCM

 

The S369 is certainly an option as it is the same frame, same 80mm turbine (the heavy bit for spool) but has more compressor. Again, what are people's thoughts on spool with a +3mm compressor inducer but identical sized turbine? The Compressor exducer is identical to the S366.

Only drawback really is that the S369 is a good $200 (and often more) than the S366 whereas the only difference is the +3mm on the Compressor inducer only. Is it worth it financially (x2 turbos).

I've inserted the Compressor Maps for the S369 below - what do you reckon?

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Thoughts, feedback or ideas gentlemen?

Thanks, Adam.

 

There's nothing wrong with the 66mm for your goals imo.

 

I'm inclined to agree, particularly in view of the additional costs associated with the S363 and S369 (+$400 for a pair) when the gains are so marginal. There's almost nothing in it as far as compressor map efficiency goes.

Any idea of street-ability (spool characteristics) on a 9:1CR 6.0 manual?

 

What heads, and cam? That's a lot of turbine, and I'd worry it may be a bit laggy, especially with a manual.

 

Heads are stock 6.0 LS2. Planned cam will probably be a mild turbo cam like this: https://www.liljohnsmotorsports.com/stage-ii-turbo-cam-226-231-605-598-113-4.html

So do you think the S363 with the smaller 76mm turbine (vs 80mm of the S366) would be an improvement? Is it $400 better?

 

My input is not to over complicate things. It will snowball quickly. For 16lbs you don’t need to “build” the engine. Leave it “as is” It will be fine... Any turbo mentioned would “work”. Go with the cheapest and easiest to package. S3XX platform is great, but expensive for what you are doing and physically larger and harder to package than necessary. S256’s would work for what you are doing.

For your goals, you want “small” turbos. That’s the whole point in doing a twin setup with a manual car IMO. You size the turbos small enough to maintain relatively low back pressure and provide good response. You don’t need 1400hp worth of S366’s to run 16lbs on a mild 6.0.

If you are set on twins, go small. Something like the 61/65s from VS racing would work really well and be much more responsive. You can get similar turbos on E-bay for under $300 each.

I run a pair of GT35 .68 T3’s 64/60 billet wheel china turbos on a 5.3. It’s VERY responsive. Set on 15ish lbs with a mild cam and it’s a MEAN street car. I have to do all kinds of things to dumb down the power for traction and I run MT drag radials.

 

Thank you Forcefed - there is a certain wisdom in your words and 'keeping it simple' has always served me well as a philosophy. I also like that you speak from clear experience rather than speculation.

I would be really grateful if you would clarify a few things for me from your own experience.

First, the CR of the stock LS2 is 10.9:1. That seems pretty high as I understand it for a boosted engine. Procharger limit their boost to an intercooled 6psi on the LS2 GTO kit - they say 'because of the CR'. https://www.procharger.com/automoti...al-motors/pontiac/2006-04-pontiac-gto-ls1-ls2 Do you think this is 'safety overkill'?

Next question is regarding the 'small turbo's'. Whilst I agree there is no need for 1400bhp of S366's on a street car - I put those forward as an idea because of the frankly 'perfect fit' on a compressor and turbine map in terms of peak efficiency (see above images) where the plot is right through the centre of the islands for rpm / pressure ratio / turbine flow. When I plot a pair of S257's (57.2mm compressor inducer), the compressor efficiency drops as low as 0.52 as opposed to the 0.72 minimum efficiency of the S366. I appreciate this is just a graph and not a real world application but I was wondering about your thoughts. Also with a 70mm turbine wheel at 16psi the S257 turbine map is way out of efficiency, ideally needing at least a 74mm wheel. Again it is just a graph, so from experience would you say you have flexibility to cross the 'turbine line' without real world choke or temperature problems? Maps below:

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I'm not trying to knock holes in your help, to the contrary I am extremely grateful to hear from someone with real experience. I just want to be certain this approach is the right one for me. Looking on the LS forums there seem to be plenty of people at 600-650rwhp with no problems on bone stock engines. There are also people at 750-800rwhp with a good fuel system, turbo cam and meth injection for insurance - but otherwise a stock bottom end. Are there any common sense mods like head-gaskets or ARP head bolts that you'd recommend or just leave it all be?

Many thanks and please reply soon,

Adam.

 

Really need to decide on a power goal and type of fuel you will be running. 16lbs on a 9:1 engine may make the same power as 12-13lbs at 10.9:1. With nice flowing heads and a cam 8-10lbs may make the same power at 16lbs on a “stock” 9:1 setup. So there are a lot of considerations.

With a good intercooler, 100 octane fuel, and water/meth I think you’d be plenty safe. The cam used plays a roll. As well as loads placed on the engine and of course the tune. With light timing and boost in the peak TQ areas I believe you’d be in the clear and then some.

Engine management is HUGE. I’d spend the money there and run factory engines. Tearing into a perfectly good engine doesn’t make much sense to me. You literally need nothing… stock cam, head bolts, head gaskets rod/main bolts etc… Most failures are due to tuner error, then factory parts (or aftermarket) are blamed. These engines were put together extremely well. Most of the time people do more harm than good when they tear into them. How many miles are on the engine?

Look at the LB per min of flow at the pressure ratios you’ll likely be at and less at the efficiency islands of the map. “Most efficient” and “quickest spooling” won’t be the same. Using those calculators is great for a slow spooling super-efficient monster HP Bonneville salt flat car… less so for a manual trans street car. Figure if it still flows 50lb a min and you have 2 of them… that’s still enough flow for 1000ish HP.

IMO you will want to sacrifice efficiency for quick “spool” . Which will translate to higher drive pressures and less efficiency. An “efficient” setup with super low drive pressure is usually unpleasant to drive when running a manual trans street car in my experience.

I personally don’t mind “lag” in auto trans. drag cars as you spool the turbo once at the line and remain in boost the entire pass. Lower you go compression wise the more “cushion” you’ll have in the tune. You really need a tuner with a clue when pushing the higher compression boosted setups… but it can be done.

In your situation I wouldn’t invest a lot in the turbos or engine initially. Pick up decent set of china 60ishmm turbos (VS racing has 61/65’s T4’s for $250ish shipped) and run a 100% untouched factory engine. Spend your money on engine management, fuel system, and driveline. Run low boost and learn to tune and read plugs while bumping boost slowly. Plugs will tell you when to stop before damaging the engine if you know how to read them.

 

In terms of power, it seems we can safely do 600rwhp (which I guess is scary to start with)... and then as you say slowly bump the boost up to I would say 800rwhp at the max. I would be surprised if you could get that down through non-slicks anyway in a manual street car.

When you say 'engine management' are you referring to tuning the original GM software or converting to an alternative ECU?

The motor has done about 70,000 miles and has been well looked after as the previous keepers were all engineers and meticulous about servicing, oil, filter changes etc.

I'm looking to go with a couple of Bosch 044's or a pair of Walbro 400's to keep the fuel safe along with filters, rising rate regulator and bigger lines. Do you have any personal preferences here in terms of reliability vs keeping the cost reasonable?

When you refer to 'driveline' do you mean upgrading anything beyond the clutch? How does the T56 fare with boost? I see you can spend silly money on making them bullet-proof, but I guess you'd say if it doesn't need it - leave it alone.

Yes I can read the colour, specs of metal on plugs from my limited experience.

Thank you again for your help. It would be nice to get it right first time.

Adam.

 

I would run an aftermarket ECU. The Mega Squirt is my ECU of choice. The power management features are great for the cost. Multiple boost control strategies… (boost by speed, gear etc) Traction control. Progressive timing controls, 2-steps, rev limiters, alcohol inj control, AFR safeties, auto tune, etc…. the MS3 ECU is plenty. No need for their more advanced ECU’s IMO.

My only concern with a low mileage engine like that is ring gap. If you start adding bunch of heat to the chamber, ring butting could occur. Though if the tune is conservative with a decent amount of water/meth keeping things cool it’s less likely. Only gambling a stock piston. Which isn’t much of a gamble when you will likely be fine.

Are you thinking about a cam? At 400hp stock (usually underrated) you are talking about roughly making 25 CHP or so per pound of boost. So to hit around 600 crank we are only talking 8ish lbs of boost. I’ve seen 470whp on a manual trans LS2 setup with a cam and exhaust system. At 470 crank you are talking 30hp or so per pound. So the more you make NA the less boost (heat) will be needed to hit your goal.

Drive line as in all of it… trans, rear end, driveshaft, clutch/PP. When I say “leave it alone” I’m only speaking about the engine.

I’m lacking pretty severely with T56 experience. I mainly do auto drag cars. I hear nothing but bad things about a “stock” T56. I’d think at minimum you’d want a beefy Clutch/PP of some sort. If you have an 800hp end goal. You’ll need to address the transmission for sure… at those power levels a manual trans is an very expensive route.

Either of those pump setups would work fine. Factory fuel rails are fine. You can even use the factory fuel lines with additional pressure as a crutch at the power levels you are talking about. Just ensure the pumps have proper wiring/amperage. AEM380s are another good moderately priced pump. From what I’ve seen the 044 and AEM380 do better at higher pressures than the intank 450 walbros.

You also use an intank pump like the walbro 400 to feed into an AEM380 inline. This will make for an easy install with the factory tank and allow the AEM380 to work more efficiently at higher pressures.

Good site on plug reading.

http://www.wallaceracing.com/plug-reading-lm.html

 

Again thank you for this golden information. I've done some research into the MS3 and it seems like a good all-rounder - particularly with the addition of a knock sensor or two. How trustworthy is the 'auto-tune' feature on this? Do you just start from an initial base, wastegate for low boost mechanically via springs and let the software do its thing... gradually building by keeping timing, fuel and afr in check as the boost is slowly raised?

My car already has a decent exhaust so I guess a cam may be a wise investment. The original plan (as part of a forged bottom end) was to add a Brian Tooley (or similar) mild turbo cam. https://www.briantooleyracing.com/btr-twin-turbo-stage-ii-cam.html - It'll probably be in the $550 range with shipping and UK import tax, but as you say a cam can work well for efficiency requiring less boost and heat. Would you recommend doing the springs at the same time as the cam for the relatively minor additional expense?: http://www.sho-mespeed.com/cat3/pro...ith-tool-steel-retainers/category_pathway-882

I'll have to look into the T56 trans. The information does seem pretty sketchy. I'll do the clutch and see what happens at low boost. I guess the weakest point will make itself known.

I'll take your advice on the 044 and AEM380.

Thank you as always, Adam.

 

Ha! I dunno about golden, but I’ve done a few and happy to share. Wish I had more of a helping hand along the way when I started!


EFI source sells a complete MS3 plug and play kit for the LS engines. I had mine installed in a few hours and the car fired soon after. Autotune is very trust worthy IMO. But as with anything “race” it’s only as good as the tuner and hardware used. I used Tuner Studio’s (MS3 software) VE calculator to build an initial map, play with idle a bit, flipped on the auto tune and went driving. WOT tuning is very simple and the auto tune makes short work of that. Getting the idle perfect in all situations as well as light load and throttle transitions are what takes most of the time. “Sloppywiki” has a TON of good information and he supplies his tunes for free. He has done many LS turbo swaps, so quite a few maps to choose from.


I like to pop the spring out of the WG for the initial drive. This allows you to get the NA tune dialed in somewhat without worrying about boost. You basically setup a desired AFR map with RPM VS manifold pressure. Enable auto tune, and drive. It will automatically adjust the fueling map to hit your targeted AFR. (it will not autotune timing). I basically target 14.5 in light load and idle cells. Target 12.5 at 100KPA (basically Wide open throttle) and 11.5 for anything above 100kpa (in boost).


Start with ridiculously safe timing on LS stuff. High Compression and big cubes like you have won’t take much! Esp near PK TQ RPM. I’d start with 10* in boost on the whole map in your case initially.


After you get the “NA” baseline autotuned, throw the lightest spring in the WG and make a low boost pass. Confirm the auto tune has the AFR in check and that boost is in control. If all seems well, toss in a new set of plugs and make a quick pull. Ideally you’d install the new plugs on the side of the road make a pass and immediately shut down and remove/read them. The more idle/cruise time you have on the plug the harder it will be to read. If the plugs look ”good” find the hottest looking cylinder and swap a single new plug in/out of that cylinder when tuning.


Then bump the boost up slowly, occasionally reading plugs to make sure all is well until you get to your desired max boost. With timing still locked at 10* it will feel sluggish until you go in and fine tune the ignition map, which should always be done last. You can run darn near NA timing up to 4-5lbs in most cases. This will wake the engine up a lot and help transition into boost quickly. After 5lbs or so I like to take it slow and bump overall timing a degree or so at a time while watching the hottest plug.


90% of this has been done if you start with one of the “sloppywiki” maps.


Tough call on the CAM. Tooley knows his stuff, can’t really go wrong there. But it’s not what I’d call cost effective to blow a grand or more on a cam swap kit. I would defiantly upgrade springs. Though which set to go with depends how radical you go with the cam. The more radical you go the more expensive it gets as you will need/want dual spring kit, beefy pushrods, rocker arm trunnion upgrades, lifters, timing sets etc… Also DOD/AFM/VVT removal parts may come into play as well. By the time it’s all done you can have 2k in a “cam swap” Which is bogus IMO. To get started (esp with a stock trans) you could try just running the factory cam/springs. Once you open up a motor it’s hard to stop “upgrading”. Snowballs into a giant money pit quick!


Good luck.

 

Once again - awesome advice. I've been watching a load of Sloppy's stuff on youtube - slowly working through his play list. Loads of really profound / simple / cheap advice on there regarding LS builds.

I have struggled to find any of his 'base tune' maps. I have looked many times but am obviously missing them somewhere. I don't suppose you have a link to the relevant page? It would be greatly appreciated.

I'm starting to learn about the flexibility of Mega Squirt through Sloppy's videos although what to buy up front (I know you recommend MS3) is a bit daunting as it would be expensive to get wrong. Would I be best contacting EFI Source with my setup and goals and to take their advice on an LS ready kit or would you recommend certain specifics?

Thank you so much.