Power AdderGetting a Supercharger or Turbocharger? Thinking about using Nitrous? All forced induction and N2O topics discussed here.
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I have ran a procharger D1-SC blown motor, a couple of nitrous motors (one of which is current). After adding up the cost of bottle refills alone over almost 4 seasons, i could shoot myself for not doing another blower of better yet, turbo build!. Here's the deal, i've spent a lot of time combing turbo forums.com(not a member, just use the search feature) and think i have the kowledge to put together a turbo motor SAFELY lol! I was just gonna tear my 355 nitrous motor and just change the pistons to get the desired CR(8:5:1) with 65cc chamber AFR 195cc eliminator heads....the crank and rods are 4340 forged units and run a T4 flanged S475 with 1.10 a/r turbine and call it good....but i'm getting the 383 S480 T6 flanged with the 1.20 or the 1.32 a/r turbine bug, one thing turning me off from this one is the MAMMOTH size of the S480 T6 turbo!! will it fit in a thirdgen or is it easier to go twin T60-1s with .68 a/r turbines with 3" dp instead of the S480's 5" dp.....where the hell would i route that on a thirgen? granted i have no ac stuff, flat panel on the firewall, battery relocated, no charcoal cannister etc.
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You could probably get a big single in the area between the engine and battery tray on the passenger side. With no AC box you can get a huge downpipe in place. If you go twins I'm thinking 2.5" downpipes would be fine and certainly easier to route for the driver side. Anyway, keep us updated on your project. It will be a blast!
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1987 Iroc 5.7 - Megasquirt II 3.0, WB O2, 3 Bar, single T70 turbo, 8 psi, Cold AC!
ZZ3Astro, how does your car feel with boost? i've never driven a "good" turbo car before....my girl has a WRX but that doesn't count everybody at my track with boost says i'll never look back!! At the last test n tune a few days ago before the track closed for winter, i was talking to a guy with a buick GN...he was running 11.40s @ 122 on 18psi with a V6granted our track altitude is a stinking 5280ft above sea level(denver). That just put in perspective what i could do with a built 383ci with the right turbo(s)
I can tell you this.. last week I was planning to hurry up and get the 6AL and fuel pump upgrade installed so I could turn up the boost. But then I decided I like it where it is right now for the time being. Part of that is I want to have the money available to resolve any problems that might come along with higher boost and part of it is that it's so much fun already. I can't stop myself from taking the car out for a drive all the time. I can't imagine something breaking and being without it, so I decided to take it easy and work on some cosmetics before going crazy. I'm seeing full boost pretty fast, especially considering I don't have a stall yet. If I'm cruising along at say 2500 rpm and stomp the pedal, and say "one thousand one" I will have full boost by "one thousand o.." Of course full boost being 7 psi but it ramps up very quickly once it starts and I think it would hit 15 just about as fast. The feeling of a turbo car to me is kind of like being a passenger in a fast car. The turbo decides when you will get full power, and you are along for the ride. I don't mean it has to be laggy - there is just something about putting the pedal down and getting a certain amount of power, and then even more follows. Thinking about it makes me want to go drive it right now!
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1987 Iroc 5.7 - Megasquirt II 3.0, WB O2, 3 Bar, single T70 turbo, 8 psi, Cold AC!
I see why you are getting full boost so fast.....you're running an mp t70 with p-trim wheel on a 350 right? whats the a/r on it, .81, .96? a t70 will generally have a quick spool on 350ci motor based on what i've read but be careful of backpressure up top though as the turbine wheels offered on a t70 is a little on the small side for a 350ci motor, a t76 will treat you right on a 350/355ci motor, i've heard from many reputable sources. How much hp/tq are you making on 7psi and what are the engine specs if you don't mind.
It's a .96 A/R and you're right, it's relatively small with a maximum of 450-500 hp. My engine is a completely stock 5.7 except for injectors and the megasquirt. I'm planning to keep the engine specs close to stock when I rebuild it, except for forged internals and a slightly better cam. Debating on heads as well, but I'm not trying to set any records with this one. I figure when I get 20 psi out of it, the performance will be quite satisfactory! Most likely I'll end up with a 67mm turbo and around .82 A/R when all is said and done.
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1987 Iroc 5.7 - Megasquirt II 3.0, WB O2, 3 Bar, single T70 turbo, 8 psi, Cold AC!
leeperryracing,
What are your goals? Personally, I wouldn't go any smaller than the 96mm TW, 1.32 A/R turbine for a race 355+ CI engine. The BW S400 series can fit up to a 88mm inducer wheel with the JD/race compressor housing. Dave said it is a $550 upgrade and flows about 1500 FWHP. The 80mm is good for about 1200 FWHP.
You could always go the MP T70 twin route. The BW is a stronger unit and I think is more reliable for high boost ratios.
As for downpipes.........The size depends on the HP you want. It isn't a matter of twins or single. A single 5" pipe has an area of 19.6 in^2, two 3" pipes is only 14 in^2. So the 5" has more HP potential, but do you really need it? It all depends on you HP goal. A 4" single DP would probably work fine for you if you are under 900 FWHP.
EDIT: In terms of sizing the turbo, pic a peak HP goal and compressor. Then a desired spool rpm and turbine. You need to be realistic in that you don't choose a giant compressor with a tiny turbine. The turbine would choke it. A forged assembly with AFR heads and mild to race cam would work great with a 75mm or 80mm inducer S400 with a 1.32 A/R turbine, 96mm TW.
EDIT AGAIN:
I forgot to mention something. You said you are just searching TTF.com. You are missing out on not being able to see the turbo classified ADs there. It only shows up when you are logged in so you need to be a member so see it. Some good deals there. I picked up a used MP T70 (70mm CW and .96 A/R turbine) for $120 shipped. I see some large Garrett and BW S400 series for sale there for decent prices. Anyway, I think becoming a member just for that is worth it.
i was talking to a guy with a buick GN...he was running 11.40s @ 122 on 18psi with a V6granted our track altitude is a stinking 5280ft above sea level(denver). That just put in perspective what i could do with a built 383ci with the right turbo(s)
Those cars flat out kick @ss. I'm still contemplating the purchase of a TTA, as now is the time because you can pick one up for very cheap. My buddy John ran a 10.98 with a bone stock Grand National (full weight), running an itty bitty TA49 turbo....
leeperryracing,
What are your goals? Personally, I wouldn't go any smaller than the 96mm TW, 1.32 A/R turbine for a race 355+ CI engine. The BW S400 series can fit up to a 88mm inducer wheel with the JD/race compressor housing. Dave said it is a $550 upgrade and flows about 1500 FWHP. The 80mm is good for about 1200 FWHP.
You could always go the MP T70 twin route. The BW is a stronger unit and I think is more reliable for high boost ratios.
As for downpipes.........The size depends on the HP you want. It isn't a matter of twins or single. A single 5" pipe has an area of 19.6 in^2, two 3" pipes is only 14 in^2. So the 5" has more HP potential, but do you really need it? It all depends on you HP goal. A 4" single DP would probably work fine for you if you are under 900 FWHP.
EDIT: In terms of sizing the turbo, pic a peak HP goal and compressor. Then a desired spool rpm and turbine. You need to be realistic in that you don't choose a giant compressor with a tiny turbine. The turbine would choke it. A forged assembly with AFR heads and mild to race cam would work great with a 75mm or 80mm inducer S400 with a 1.32 A/R turbine, 96mm TW.
EDIT AGAIN:
I forgot to mention something. You said you are just searching TTF.com. You are missing out on not being able to see the turbo classified ADs there. It only shows up when you are logged in so you need to be a member so see it. Some good deals there. I picked up a used MP T70 (70mm CW and .96 A/R turbine) for $120 shipped. I see some large Garrett and BW S400 series for sale there for decent prices. Anyway, I think becoming a member just for that is worth it.
junkcltr, to be really honest with you i'm looking to break or set any track records....just want a nice running, reliable car that can go head to head with the best of "em. I KNOW i can can get into the mid-low 10s with the 355ci with the right turbo, even at this altitude especially when i see countless fox-body guys over at TTF.com running sick times with tiny 302,306,331ci motors. I'm more than likely gonna get a 3.75" crank and go with the 383 if i'm gonna tear into the motor that far to change pistons I've always noticed that you are one of very few on TGO that know their stuff about turbos.....my goals with the 383 is/will be around 750-800RWHP ONLY because i'll want the 700-r4(bowtie od level 2 w/edge 9.5 converter) behind it to stay alive long enough until i pony up for a bullet proof TH-400 with a gear vendors overdrive unit. The question is, if going single with a desired full spool time of around 34-4000rpm, no later, which single would you recommend? and if i decide to go twins with around the same spool time, which twins? I plan on shifting around 6200rpms with 6500 being the absolute MAX....I think its stupid to wind blown/turbo motors to 6800+ rpms.
P.S- I think i will go a head and become a member on TTF.com so i can catch some deals! thank you.
I would go with a 75mm or 80mm inducer CW, and a 87mm or 93/96mm TW. Since you favor decent spool time over exh. back pressure I would go with the 80mm CW and 87mm TW. The Garrett GT4508 and a flavor of the BW S400 would work great. As for twins, a 60mm CW unit from MasterPower would work well. Overall, the best band for the buck is the S400 with a 87mm TW and 80mm CW when going with a single. The MP twins would run about the same price.
Why go with a TH400 with the 4th gear unit when the 4L80E will do everything you need and do electronic shifting? I have been messing with the 427_ECM that controls a 4L60E/4L80E. I hope to have it running a 4L60E with 2-bar boost by next spring.
the 4L80E??.....I don't know about those really, i've heard they're just glorified 700r-4s and will crap out behind REAL power also, not to mention they want a small fortune for them. I've changed my mind permanently this time....i'm going the twin turbo 383 route with two master power t61 units with a .68 a/r, I know a single or tt 355 would be more than enough but there's a greedy side of me that i can't contain
spoke to my engine builder today and he talked me out of a stock block and into a Dart SHP block(4.125 bore with 350 mains) and they're already clearanced for a 3.75" crank so im gonna end up with 400.98ci, 401ci pretty much...i'll have to step up to 2 master power t64s intead of 2 t60s that i had planned for the stock block 355/383
I would just go right to the MP T70 if putting twins on a 400ci Dart block. If you want to run on the lower side of HP and desire fast spool go with the .68 A/R turbine housings. You can always buy the .96 A/R turbines later on if you want more peak HP. Keep an eye on the exhaust back pressure if you decide to try and go high HP with the small turbines.
The turbines are relatively cheap and you see people wanting to swap sometimes at the turboforums.
junk, wouldn't 2 mp t70s with .68 a/r be good enough for 400ci up to say 750rwhp? i think they're also offered with .70 a/r also.....don't know if there will a noticeable difference going from .68-.70 though, i doubt it. Orr89Rocz and i are gonna have pretty much identical setups as far as cubes and turbo layout but he's always said the mp t60s on his comes on INSTANT and i wouldn't want that, which is why i was thinking t64s but with the same .68 a/r as the t60s....in theory i should spool a little later than his does. Max hp is not my ultimate goal so i'm wanting to be fully spooled or near there by 4000rpm max so i don't have to rev to moon....my bottom end and valvetrain will be happier i think.
junk, wouldn't 2 mp t70s with .68 a/r be good enough for 400ci up to say 750rwhp? i think they're also offered with .70 a/r also.....don't know if there will a noticeable difference going from .68-.70 though, i doubt it. Orr89Rocz and i are gonna have pretty much identical setups as far as cubes and turbo layout but he's always said the mp t60s on his comes on INSTANT and i wouldn't want that, which is why i was thinking t64s but with the same .68 a/r as the t60s....in theory i should spool a little later than his does. Max hp is not my ultimate goal so i'm wanting to be fully spooled or near there by 4000rpm max so i don't have to rev to moon....my bottom end and valvetrain will be happier i think.
Turbine wheel size and A/R have more of an affect on spool time.
If you want 750 RWHP and quick spool I would go with the MP T70's with the .68 A/R turbines. The .70 A/R you mentioned would be a zero difference change from the .68 A/R.
Later on if you want to up the HP to 1000-1200 RWHP then swap in the .96 A/R turbines.
With the .68 A/R turbines I am estimating your exhaust back pressure (EBP) ratio to be 1.8 - 2.3. Fine for a street setup with good peak HP. Depending on heads and cam you should be in the 16 PSI-ish range on the intake side. Good luck getting it to hook up on the street.
EDIT: Put good flowing mufflers on the thing to get the EBP as low as possible. Look at the Dynomax website. They give the CFM flow rating and equiv. HP for their mufflers. You want mufflers that flow about 500 HP each. That means something like two of the 3" IN/OUT ultraflows. Personally, I think they are too loud without turbos, but with turbos adding to the muffling affect then it makes them fine.
I think i can have a LOT of fun with twin mp t70s with the .68 a/r at the track and the street. Considering my 355 this past season was running consistent 11.50s @ 119 on a 125 shot up here at 5280ft elevation....you sea level guys have it made! With the new setup i should be in the 10s easily....i'll be limiting it to high 10s probably so that this 700r-4 will live until i fork over for a manual valve body, transbraked 4l80e(i gotta have the overdrive lol!) then i'll switch to the .96 a/r exhaust, crank up the boost and let her sing.
everybody at my track with boost says i'll never look back!! At the last test n tune a few days ago before the track closed for winter, i was talking to a guy with a buick GN...he was running 11.40s @ 122 on 18psi with a V6
granted our track altitude is a stinking 5280ft above sea level(denver). That just put in perspective what i could do with a built 383ci with the right turbo(s)
I've always noticed that you are one of very few on TGO that know their stuff about turbos.....my goals with the 383 is/will be around 750-800RWHP ONLY because i'll want the 700-r4(bowtie od level 2 w/edge 9.5 converter) behind it to stay alive long enough until i pony up for a bullet proof TH-400 with a gear vendors overdrive unit. The question is, if going single with a desired full spool time of around 34-4000rpm, no later, which single would you recommend? and if i decide to go twins with around the same spool time, which twins? I plan on shifting around 6200rpms with 6500 being the absolute MAX....I think its stupid to wind blown/turbo motors to 6800+ rpms.
