What about suspension, front/ back/ rear gears?

 

Front has Lakewood 90/10 struts, moroso trick front springs (big block front-end weight). Rear has Lakewood LCA's, weld-on LCARB using lower hole, single adjustable shocks, Spohn tq arm that mounts to the trans crossmember (and is not their newer really beefy one). 3.54 gears, and wouldn't mind something more like a 3.23 or 3.08 except that nobody makes one for this dana based axle. TH400 trans if I haven't said that yet.

My computer can also record exhaust backpressure, so sometime I'll make a connection for that. I'm sure it will show low values that would indicate my cam could be a much more n/a looking grind. This meaning it could have way more exhaust duration and less LSA.

 

Just for the hell of it, I piped this setup to just one turbo and talk about spooling! Didn't have enough tire 275/60/15 to stick down a good launch, but had it banging on the 3800rpm limiter and still made it to 4000rpm and 17psi. Exhaust pressure is insane holding pretty steadily in the 32 psi area all the way down track. It can make about 17psi just after a shift, but tapers off to 11ish just before a shift. Also had cyl 1 and 8 melt off half the ground strap from the plugs, but still compression test just fine. Because of this, no proper 1/4-mile time.

So, twin 67mm turbos are on the way with turbine wheels of 74.1/64.6mm and .68 a/r instead of the oversized 87.4/77mm 1.05 a/r that my current turbos are.

 

2:1 back pressure isn't bad at all IMHO. Just can't run a huge duration cam. Hell my 4 cyl was right around 3:1 at 36+psi. What do you think caused the detonation issues? Plugs to hot? Fuel? timing? Bet those .68's will work great!

 

i'm guessing that the motor went into an untested area of the tune since it never previously saw large boost until like 5500+rpm instead of the 4000rpm area that it happened at with the single turbo. The cam is setup to accept some exhaust pressure but is rather large: 262/252 @ .050 116LSA

 

Did you install the 305?

 

That was with the 406, but yea I ran the 305 for a couple weeks. Nothing spectacular happened, just couple things on post 52 above.

 

Well next time you need a short term motor hit me up. Cheap 350 in the garage depending where you are located

 

So I tried twin 67's with .68 a/r p-trim exhaust sides and they work fairly well, but I want more. I can get 5.5-8psi in about 2.5 seconds on the TB and they spool to peak boost pretty quick. The bad thing is that at the same boost pressure, it pulls 6-7mph less than the gt45's. This comes mostly from exhaust pressure since the smaller ones hold 25psi in the headers where the gt45's are only at 15psi. The solution for both of these problems is what I've been avoiding, but here is the beginnings of what will be a compound turbo setup:
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I had the last setup made to easily convert to running only a single turbo, and running one of the 67's got me 14psi in less than a second on the TB. I also might try out with this setup a 76mm .96 p-trim turbo I borrowed from a buddy. The atmospheric turbo(s) will be mounted in the rear of the car and be either the gt45's or the 91mm Precision I was using a few years ago. The deciding factor being if I happen to sell the 91mm or not. If you haven't asked yourself this yet, yes my barn is freakin turbo mania with all these things.

 

Sounds like weekends well spent to me!

I think the pump gas is kill'n you. I'd be really curious how a cam swap and some good old e85 or meth injection would act with the higher back pressures.

Although the gt45's did make more power at less boost, did you try turning the boost up higher on the 67's? Or were they out of steam? Over in the famous "how long till it grenades" thread, they ran .63 GN turbos with a much smaller exh. wheel than the P-trims to 25.5 psi on there small block. I'm sure the back pressures were threw the roof on that setup, yet it still performed very well!

Good luck, keep us updated!

 

I did make the switch to e85 also, and all things the same it is slower by 2-3mph. I'm not impressed with it, but I do still plan to continue using it. Took my injectors from 70's duty cycle to 90's, and basically the entire tune had to richen up right about the 30% that people say. I have yet to see what more timing will do though and with 18psi I've been using 24 degrees this season. There might be some big power in more timing since n/a it likes 36-38 degrees, I'll just have to creep my way up till the motor stops liking advancing. The 67's are far from out of steam. Still with these undersized wastegates I had it setup like a normal system, and they easily hit the safety I have in the tune at 22psi.

 

Makes sense if you made no other changes that you'd be down slightly on power. There's less energy in an alcohol based fuel. Every combo I've ever had made more power with boost than timing. Why not leave the timing alone and just add boost if your searching for more power? Thats when the e85 really shines IMHO. Timing is tricky on alcohol based fuels and you have little to no warning of detonation. (unlike pump fuel) Crank that sucker up to 28psi and I think you'll be singing a different tune.

 

This might sound strange, but I'm trying to get back to where I was before going faster. A few years ago I was running a stupid loose converter and wide tires. It'd pull the front wheels up and run mid 9's at 14xmph with 15psi, but the trans ran real hot and the engine never rpm'd less than 6800rpm the entire pass...and thus I was also out of gear since it was at like 25%+ converter slip. I'd like to again see at least some kind of 9 second run and 14xmph before going farther than 15-18psi. I'm also planning to put some pre-compressor injectors, since I could use more fuel and have these free injectors from a trailblazer and should show cooler intake temps as well as better turbo response/efficiency.

IDK about this detonation warning you speak of with pump fuel, I've blown a few pistons with no warning I could tell. I've always read from people how they love e85 since it is almost hard to hurt a motor using it.

 

Again, all just MHO. You obviously know what your doing. Been following this build for a long time and I'm just trying to help. Shooting for the same goal with a different setup is a tough one. Capatalizing on the current setups strengths seems more beneficial? I was thinking for motor longevity you'll put less strain on things with boost than risky experimenting with high timing.

As far as detonation goes, pump gas/race gas gives you a great/easy to read heat indication on the ground strap of the plug. Assuming a person is running a new plug each lap and reading it to dial in the timing. You also tend to get light peppering and signs of detonation well before blowing holes in pistons. Alcohol fuels are much harder to read. And you get little to no warning on pre-ignition. I've seen a e98 motor run it's best at 32* total with a clean plug reading, then blow a hole in the piston the very next pass at 32 and 1/2*. Since the owner has dropped timing down to 22* total and runs much more boost.

Ethanol is a great fuel I run it on all of my cars. Daily driver is a 9:1 4 banger using e50. It sees 34 psi daily. 15* of total timing. ...and it doesn't miss the higher timing one bit!

 

Pretty much at a closure for this now. Smaller/less turbo would show higher psi sooner, but didn't really produce power in line with the boost since the exhaust pressure was up as well. I also wasn't liking the idea of power being so dependent upon boost, such as having enough boost to launch with. I was seeing two choices left for me. Could have either gotten more launch rpm by way of a higher stall or by making more power when not in boost. The valves needed a good clean up, so with the heads off I put in some flat top pistons to move from 8.5:1 up to 10.5:1. The low drive pressures of the gt45's brought me back to using them as twins. I've been burning e85, which helps allow compression like this with boost. Quite pleased with its first few passes running a touch rich and little low on timing. It spun every launch, while still managing 1.5x 60's, and clicks off 10.0's@ 136 from the 7psi my new twin 60mm gate springs hold it at. I upped it to 10psi, and had to do some heavy pedaling through 1st gear, but came out with a 10.1@ 140. This also maxes out the 95lb injectors, and I plan to put additional injectors up stream to supplement as well as aid in air charge cooling. Something I wasn't expecting is that even though it stalls the converter higher, spool up is actually pretty lame as it launched on average with 2.5psi.

 

Lets see some pic's of the current setup!

Are you using any kind of anti-lag? Although if your pedaling 1st that badly more pressure might not be what you want? Dropping the timing down to -10* or so and throwing a ton of fuel at the tune (in the spool area) made a huge difference on my launch boost.

Not that adding injectors doesn't sound like a great idea, but if you have the fuel pump you can push those 95lbers alot farther. Esp at those low boost levels. Crank that base fuel pressure up. Guys making 850whp here on 80lb injectors on e85 w/ 67psi of base fuel pressure (28lbs of boost) goes a long way. Just keep the total pressure under 100 and the injectors will be fine.

 

The pedaling should be solved whenever I come up with some wider wheels to fit the 325's on the car again as I'm still running the 275's. Higher fuel pressure isn't a bad idea, and certainly possible since my base at the moment is 42ish. I've liked the idea of some fuel coming in early like when some inject meth into the compressor, and have heard of better spooling and cooling with this. I was thinking of trying some anti-lag again with this high compression too.

 

Just tried a rev limiter at 3300rpm on the TB and that did nothing for spool. Didn't try dumping fuel at it though, next time. Got a current pic for ya:#ad

 

Looks awesome! The rev limiter and the brake won't do it alone. (at least it didn't for me). You have a to get the timing in the negatives so the exh valve leaks combustion out pre turbo to aid in spool. -10 to -17* seems to be the sweet spot for most. If you have the ability add fuel to that and you will get larger 'bangs' and it will spool faster. You also need a way to quickly ramp the timing back up to normal and removing the additional spool fuel. What engine management are you using again?

Keep it up ! That things got serious potential.

 

I'm using big stuff 3. If I remember right, I don't think it'll let me go any past 0 advance. It only has a separate timing table activated by switch where I can set timing vs rpm, and after release it returns to the normal table. I could put in a pwm in that wire so some of the fires are at normal advance, unless making it just flat out 0 degrees works. Fuel changes are doable also since it's only in a certain area when trying to spool on the TB. I kinda remember a time where, even with normal timing, it spooled up noticeably faster when I had AFR's in the 9's during spool up. Over the winter I looked at a way to mist water or fuel into the exhaust that I might explore. Using a methanol nozzle might work pretty well too.