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3.2 Turbo Build
I figured I'd start a thread on my upcoming engine build and standalone tuning. I REALLY appreciate any input along the way. Hoping to also hear from those who have boosted their 3.2.
First, HERE's the car, and HERE is the rust work that I need to finish before I do the fun stuff (engine build). Build goals: - Modest power goals (320hp crank) - Highly responsive, boost should come on at ~3,250rpm...hopefully - Reliable and drivable. Not trying to smoke everyone on the road. I just want my version of a 930. Engine rebuild plan: - Rebuild the 3.2 and (hopefully) keep the existing pistons and cylinders - Shave off a small amount of the piston dome to get down to 9:1 compression (need to remove 3.5cc fo aluminum) - ARP connecting rod bolts and head studs (bought already) - Rebuild cylinder heads, twin spark - Grind cams to 964 spec? Worth it? - Thought about building the heads to redline at 7k rpm but it just doesn't seem needed. Boost: - Retain factory headers and heat - Turbo: Garrett G30-660. Any ideas on turbine AR? 0.62? - 46mm Precision wastegate - Side mount turbo on drivers side. I just seems like this is a better spot for the turbo, but I need to CAD it all up and make sure I'm right. - Turbo oil drain into lower cam cover. Hopefully I can get the turbo high enough for this to work. Not water cooling the turbo. - Water to air intercooler. Intercooler from a BMW M3. It's compact and it's performance is known. Pretty good little unit. - Various 3D printed parts to make it as factory looking as possible. Management/Fuel: - ECUMaster EMU Black (I used this this in a fully built Audi URS6. Great ECU.) - DBW throttle body - 60-2 crank sensor (Either on a new flywheel or a pulley mounted wheel. Not sure yet.) - Clewett cam sensor - Injectors? I've used ID1000's before. They are great but very expensive and overkill for this build. Will run a Walbro 255 external fuel pump. - Flex fuel sensor and all fuel lines to support E85. I'll mostly run pump gas but it's nice to tune on E85 before going to gas. - Coil on plug ignition Trans: - Rebuild 915 with factory LSD. I'll tune the boost curve to keep torque under 300ftlb through the rev range. That means something like 6 psi max at 4000 rpm. Do the billet diff covers actually help? - Clutch? Sachs Power Clutch? How much torque can these handle. I'm not launching this car so I don't need anything crazy. There's a few reasons for the water to air intercooler. I'm not running a whale tail and I don't really like the look of the intercooler covering the engine. I can remove the end tanks on this intercooler and and build custom 3D printed end tanks to integrate it into the overall setup. I should fit mostly out of sight in the engine bay. What am I missing? Open to any input and criticism too! http://forums.pelicanparts.com/uploa...1723504149.jpg |
The Garrett G30-660 is a different choice, I know. I was able to buy it for $1k and couldn't pass that up. A few reasons why this could work well.
First, it has a smaller compressor wheel / faster spool than the GT3076R (the turbo I think most people run). That also makes it a little more compact and easier to fit in side mount. It's true that these new turbos are optimized for high boost, but actually the compressor maps have a huge sweet spot. Here's a comparison: GT3076R http://forums.pelicanparts.com/uploa...1723504720.jpg G30-660 http://forums.pelicanparts.com/uploa...1723504741.jpg The red dots and line are from 3,000-6,000 rpm with boost building to keep peak torque low at lower RPMs. The yellow dots and line are the same except at 0ft elevation (I'm at 5,000 ft). The blue dot is a higher peak boost scenario :) I don't have a turbine housing yet and I'm really not sure if I should go with a 0.83 or a 0.61 AR. Any thoughts? |
320HP at the crank is way too conservative if adding a turbo and EFI, even if using a 915.
The 915 can live just fine at 300HP at the wheels. With mods it can live at 350whp as long as you let the turbo do the work, no drag starts or speed shifting. A stock 915 can handle 320CHP no problem. Reinforcement for longevity and added strength would be a reinforced side cover and larger bearing retainer. LSD helps evenly distribute the load for even more strength. I ran that combo in front of a 3.3L 930 engine in an SC for 15 years that saw variations in output from 300whp to 350whp depending on what we were testing at the time. Least expensive and problematic turbo install would be to use OE 930 parts. Install becomes plug and play with only the intercooler being custom at that point. This is assuming a standard flange pattern turbo is used. OE "Euro" heat exchangers and J-pipe would help keep the power level down closer to your target as well. Protomotive does a side mount turbo so they have those parts if going that route. |
You're probably right RaryL8. That blue point on the compressor charts is 12 psi boost. I'd guess that would be good for about 375-400 crank hp.
That said, I'm going to try to keep this build tame. My goal is to have similar power to weight ratio as a 993 Turbo. Agreed that things would be more straightforward if I used 930 parts. Doing something a little different is part of the fun for me...but we'll see how things develop. I may need to pull it in a little! Anyone know what A/R ratio you are running on your turbo? |
If you can locate a 930 or G50 box, you can relax and do wherever you want power wise. Someone will definitely scoop up your 915 to offset costs.
Hate to hear folks keeping power down due to the 915… |
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I'd definitely do 964 cam and 7k+rpm mods especially if your wanting to keep the 915 and lower power levels.
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Appreciate the input all.
Looks like people are asking for $20k for a rebuilt G50. Can’t do that. I also like the idea of the 915 being designed by Porsche and I’m good with torque staying around 325 lbft. If I build the engine to rev I could get 400 crank hp while keeping toque low. To that point…I agree…it’s probably worth the cost of a set of valve springs to allow the engine to rev to 7k+. Good to know on the CMS. I think I’ll do the trans rebuild myself and have a lot to learn before I do so. |
Also, I’m going with a 0.83 AR for the turbine housing. The video below convinced me. In the video they compare the same turbo I’m using G30-660 with both a 0.62 and 0.82 turbine housing. The 2JZ is 3L 4 valve and is somewhat similar in flow to the 3.2 2 valve 911 engine.
Their tests show the 0.83 performs better across the entire rev range. I don’t quite understand why it also comes into boost sooner, but it’s enough evidence for me. https://youtu.be/qvSibDP902k?si=WdRcsOBU8MywSmm4 |
Question for any who have a turbo 3.2. What wastegate size are you running and do you get boost creep?
I’m planning to get a Precision 46mm but I’m concerned that it’s not big enough and I’m not going to be able to keep boost down at my target (7-8 psi) at redline. Any experience? Thanks! |
46 should be perfect.
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46 should be ok, I have a 40 and I do get creep, winter project is to go larger. I've lived with it a long time, it's a .5 bar spring but intercooled and it doesn't really creep above .7 the way that I use the car.
Your 915 will be fine if you drive it like a 915-be aware that 2nd is weakish, and no clutch drop starts. Mine lasted a long time even with 120k on it and a weak 2nd sychro before a guest driver crunched up 2nd for good and I had it rebuilt. Not the fault of the turbo setup of the trans. |
Good to know. Thanks guys. The turbo I’m running is pretty large so creep might be more of an issue. I’ll stick with a 46mm and hopefully that will be enough. Tempting to just get a 50mm Garrett Wastegate now, but I did already order the Precision 46mm gate.
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Running the Tial F46 with 1 bar spring, no boost creep.
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Check up my tread .. your over thinking it .
If you have questions feel free to message me . Btw, tial 46 mm over here.. no boost creep . Good luck ! |
Over thinking it is the best part! Ha.
Good to hear ~45mm is working for everyone here. I’ll stick with that. Speaking of other thinking it, I’d really like to go with a side mount location for the turbo, similar to Protomotive’s stage 1 setup. There’s a couple photos online but I’d love to see what they do with the engine pan. Seems like they have the turbo right where it should be. |
Here’s a pic of Protomotive’s side turbo setup on a 3.2. Doesn’t seem like the engine pan would fit…http://forums.pelicanparts.com/uploa...1726283521.jpg
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No idea how that would fit. I have an early generation Protomotive kit on my car that uses the stock heat exchangers, it is "side mount" but the turbo is below the engine tin.
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Greg, is there any chance you could snap a few photos when convenient? I’d love to see how low it is and see how they routed the exhaust / wastegate. No rush, but would be great to see!
Do you have a scavenge pump for the turbo or does it just drain into the lower cam cover? |
Sure. Will do. The exhaust is not Protomotive, had a local shop do that when I changed to the gt35. Just a drain on the oil line.
The one exhaust feature that appears nice that I wouldn't do again is that the wastegate is routed into the tailpipe rather than having a zork tube. Makes changing out the wastegate a real project... |
http://forums.pelicanparts.com/uploa...1726519635.jpghttp://forums.pelicanparts.com/uploa...1726519719.jpg
Sorry, the 4 post lift isn't ideal for photos. Let me know if you need anything else. Protomotive did the air intake on a large K&N filter mounted under the parcel shelf with a pipe down to the turbo inlet. No real muffler, just a resonator. Its pretty throaty... |
One day I’m going to route my wastegate outlet to the head pipe before the muffler. I HATE the tone of open WG.
I made a muffler for mine but it’s still a little too loud. |
Its a very clean way to do it, but I need to upsize the wg due to the bigger turbo, and larger modern ones are not bolt in (v band etc ) so will need to rework the exhaust. I'm living with the creep for now running a .5 bar spring, it'll creep to .7 or so in big gears/high rpm but intercooled its probably ok that way. I don't don't often do that anyway as it involves speeds that are uncool on most roads here.
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Its a very clean way to do it, but I need to upsize the wg due to the bigger turbo, and larger modern ones are not bolt in (v band etc ) so will need to rework the exhaust. I'm living with the creep for now running a .5 bar spring, it'll creep to .7 or so in big gears/high rpm but intercooled its probably ok that way. I don't don't often do that anyway as it involves speeds that are uncool on most roads here.
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So helpful Greg! Thank you. I'm even more of a fan of the side mount after seeing this. Very nice install.
I see that the turbo oil drain is a gravity drain into the lower cam cover. So nice and simple. The wastegate location is different from what I was thinking but it makes sense. I can't quite see how the WG connects to the pre turbo exhaust. Looks like maybe it's pulling from the turbine housing. What turbo are you running? Looks pretty large. I was planning to run more muffler/resonator than you are. I'd like to keep it somewhat close to stock loudness. How does it sound? |
Correct, the w/g is on a flange on the inlet.
Turbo is a GT35r from "cough" asia. I didn't want to rebuild the original protomotive setup that runs from the heat x to the turbo, and the original turbo that Proto used back in the day was a Buick Grand National setup with the square inlet and complex bolt on outlet flange-my choices were a custom Precision or a $350 ebay thing, so I went with that knowing it might be junk. But its been ok for 2 yrs at the mileage I use the car at. Its VERY close to the back tire... Probably would have made sense to use a real gt35 and have everything done with vband. Live and learn. The "hassle" side mount is the air intake plumbing. Proto's solution was pretty good, plus you can hear the loud suck in the car if that's your thing. |
I see you're doing a standalone ecu, good call. I bought a VEMS with the thought that I'd switch to higher flow injectors and eliminate the flapper box, but at my age (mid 60's) I realized that the time I'd spend converting and tuning would likely be the equivalent of 2 years drive time for me (have other toys) so I moved it along. I do worry about afr's but the rising rate fpr has been good for 10+ years and while it's likely rich for safety I'm ok.
Are you planning on recirc for the ic and a radiator or just a spray to waste? |
I recently built a ‘95 Audi S6 and needed to do standalone for that. It’s a fully built five cylinder engine and I’m running 30 psi boost. It’s a beast and well beyond what can be done with the factory ECU. Learning to tune felt like learning a new profession. Watched lots of videos…Evan’s Performance Academy is a great resource. Took me a year I’d guess to really get the car dialed and to feel like I knew what I was doing. The problem when you are your own tuner is that you just keep tweaking things…
I’ll add knock sensors to the 911 engine but everything I’ve heard is that the engine is so noisy that they are basically useless. Will be uncomfortable to tune timing without a good knock signal. I already have the ECU Master Black for this build and I just got the ID1050 injectors. I really wanted to do something cheaper for the injectors but I’ve used them and know they are solid. Overkill for this build but they will work great. Yes planning on a radiator with a small fan for the intercooler. I’m thinking I can fit it in the front of the drivers side wheel well. Any other ideas on location? It will not have to be very big. Only time it will need to really dump heat is when the intercooler heat soaks with the engine shut off and I restart it before it fully cools. http://forums.pelicanparts.com/uploa...1727044278.jpg |
Nice.
DS fender location would be ok, my preference would be to use a ruf or rsr front bumper and center mount the rad and maybe oil cooler... |
I’m still working on the body but I hope to start on the engine in the next month or so. In the meantime I’m gathering parts for rebuild and upgrades. I figured I’d share a few photos here.
Garrett G30-660 with 0.83 turbine housing http://forums.pelicanparts.com/uploa...1729828780.jpg http://forums.pelicanparts.com/uploa...1729828780.jpg http://forums.pelicanparts.com/uploa...1729828780.jpg Precision Gen 2 46mm Wastegate http://forums.pelicanparts.com/uploa...1729828914.jpg http://forums.pelicanparts.com/uploa...1729828914.jpg http://forums.pelicanparts.com/uploa...1729828914.jpg |
Aasco valve springs and titanium retainers
http://forums.pelicanparts.com/uploa...1729829065.jpg http://forums.pelicanparts.com/uploa...1729829065.jpg http://forums.pelicanparts.com/uploa...1729829065.jpg http://forums.pelicanparts.com/uploa...1729829065.jpg Patrick Motorsport cam sensor kit http://forums.pelicanparts.com/uploa...1729829120.jpg |
Kennedy Engineering pressure plate (bought from Patrick Motorsport)
http://forums.pelicanparts.com/uploa...1729829189.jpg http://forums.pelicanparts.com/uploa...1729829189.jpg Patrick Motorsport 60-2 lightweight flywheel http://forums.pelicanparts.com/uploa...1729829238.jpg http://forums.pelicanparts.com/uploa...1729829238.jpg |
Water to air intercoolers. I bought one from a BMW M3 and one from a Mercedes 450 V8. The Benz unit was only $50 with the DBW throttle body, so I snagged it just in case. Both will flow enough air and provide more than enough cooling. I think I’ll go with the M3 intercooler as it’s a little more compact. The plan is to create custom 3D printed end tanks.
http://forums.pelicanparts.com/uploa...1729829636.jpg http://forums.pelicanparts.com/uploa...1729829636.jpg |
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I’m tired of body work so I did some noodling on the turbo location.
This started with 3D scans of the car, the turbo, and the wastegate. I’ve used solidworks my whole life but it seems to be going to sh$t so I decided I’d use the project to learn Fusion 360. After an hour of shifting things around I think this is a good compromise. There’s also a nice spot for the wastegate when the turbo is side mounted. I’ve also been wanting to try stainless steel 3D printing. It’s not cheap but neither are mandrel bends and fabrication. It’s not done but I think the organic form of the turbo inlet pipe will look pretty sweet. http://forums.pelicanparts.com/uploa...1730345732.jpg http://forums.pelicanparts.com/uploa...1730345732.jpg http://forums.pelicanparts.com/uploa...1730345732.jpg http://forums.pelicanparts.com/uploa...1730345732.jpg http://forums.pelicanparts.com/uploa...1730345732.jpg http://forums.pelicanparts.com/uploa...1730345732.jpg |
That’s fun.
I like that spot I can’t tell are you dumping the waste gate or bringing back into the exhaust? The j-pipe swap out makes sense for side mount of the turbo. I’ve seen that idea I think before. You’d want to support from the valve covers but I worry the bolts are too small? Is there a better way to support? Interesting. How much $ does printing parts like that cost? Also do you plan to scan the exhaust flange bolt area for the j-pipe bolts or weld this stuff? |
How are you ducting the induction inlet of the turbo? It's unclear to me from the really cool pics.
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This first pass was mostly just about finding the right position of the turbo and wastegate. I have not yet created the compressor side plumbing (in and out) or anything on the out side of the turbine.
The intake will be routed up and into the engine bay. I'd rather do something more OEM than a cone filter...but it might end up being a cone filter with a shroud. I'm trying to keep the wategate path straight and short...but it will reenter the exhaust stream ahead of the muffler/resonator. There will be a lot of bypass and I'm not into raw wastegate noise. The cost for the turbine intake pipe as it is in the CAD would be roughly $300 in 304 stainless. I'm not yet sure if I will reused the existing 2 to 1 that merges the two banks. I think I probably will keep it and weld it to the 3D printed part. And yes, I was thinking I'd make a bracket that mounts the turbo to the valve cover studs. The studs are M8 so the bolt is big enough, but I have not looked at the head to make sure it's all strong enough. If I'm worried about it, I'll probably just increase the number of studs that bracket mounts to from 2 to 4. |
That's pretty close to where my Precision kit locates theirs. The air intake is on a long pipe that's routed under the rear shelf with a pretty long/large K&N filter on it-protected from the weather there, but you do hear it in car. I kinda like that, but I'm sure its not everyone's taste.
As mentioned earlier, check rear wheel clearance, its close there. |
It’s pretty close to the same spot. From what I can tell from the photos, I have it pushed a little further back further in which should give me more cleance. I’ll get the wheel into the CAD and get a better idea of how much room I have. Your turbo looks much higher which is better but I don’t get how they had room for that. My current location is too low for the turbo to drain into the cam cover.
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