scottland

for the next motor im building, the compressor map for the T-88 seems to fit pretty spot on.

83 Crossfire TA

iTrader: (2)

I'd love to see an actual T88 compressor map, where are you getting one from?

BigMike92Z

83 Crossfire TA

iTrader: (2)

again, same question, where did you get that from?

Looking at it, I'm assuming that the units are lb/min? If they are I take it all of you are expecting to need something that moves enough air to feel 1300hp at 15psi, or are you just hoping to slide in inside the surge line?

85TransAm406

iTrader: (1)

I'm just learning to read a compressor map, so I have a question based on what I thought of how to read one...Wouldn't 1300 HP at 15 PSI put the compressor into overspeed, or way out of efficiency?

Dustin Mustangs

iTrader: (1)

Your right 85TransAm406. About 10hp for #/min of flow is a reasonable estimate. Regardless of 1300hp or not, that turbo is HUGE! You'd need to be on high side 400 ci to take advantage of that bad boy.

85TransAm406

iTrader: (1)

Hmmm....I do have a 406....
I have been looking at turbos for a while, but mostly junkyard turbos mostly for cost reasons, but I can seem to find a compressor maps for the Holset turbos (readily available in larger sizes). that map has me thinking though, maybe it is the way to go. I only plan on running 5500 RPMs and 10 PSI, so that gives me around 74 lb/min requirement, right? Pretty good for this turbo, i think. I've never seen a map for a T88 before, but i did see one for a GT76, and it put me way to the right of the map at anything under 13 PSI. Anyway, on topic, i guess, if I could get one of these (T88) on one of these headers, i'd go for it. I don't know if it would fit though, I don't know anything about the flanges and stuff (what turbo has what flange). I am set on a single turbo, however, but don't want to intercool (more like don't want to bother with fitting a intercooler). I could run water/alky injection, I have been throwing that idea around. Anyway, think a T88 would fit on a manifold like this, and clear a Trans Am hood?

scottland

I hate to hi-jack this thread, but im still in the planning stage and could use some good advice.

help me out with my math here. im assuming a 383cid engine, 6000rpm, 130F intercooled inlet temp, 15psig, and 80% volumetric effiencey and i come up with 73 lbs/min of airflow.

which when plotted on the map puts the compressor at peak effiencey.

while i don't know exactly what the inlet temp would be on a intercooled engine given those numbers, i think they are a bit conservative, I chose 80% VE, and i might end up going with a 406 spinning at 6500rpm.

but being that this is going into a street car, im aware that you can't operate it at 6000rpm all the time.

idealy i'd like all the boost in by 3600-4000rpm

and assuming all the same numbers @ 3600rpm you have 43 lbs/min and are just barely over the surge line.

assuming all the boost is in at 4000rpm it comes out to 48lbs/min, and im still riding the surge line.

Looking at other compressor maps, a t-81 or a t-76 might be alittle closer to what i need. but a t-76 seems too small being that 73lbs/min at 2.0 PR(15psi) puts it out of its effeicency range, and that is using conservative numbers. i'd like a little room to grow with the turbo i choose.

the other reason i am looking at a t-88 is that im seeing plenty of lt1s running 383-400cid motors running anywhere between 12-15psi on pump gas putting down 600-700rwhp, and still manage to be streetable without terrible turbo lag.

any comments would b greatly appreciated, im still in the 'Reseach' of the R&D on this project, and all the help i can get would be great. If you disagree with anything i've said above let me know, because id rather find out now, then $7000 dollars later down the road.

85TransAm406

iTrader: (1)

I came up with 94 lb/min, as you would normally assume 100% VE with a turbo engine because it will be at least that.

83 Crossfire TA

iTrader: (2)

You're reading it right, my original point was based on the idea that someone is going to try to actually get the thing built/tuned to a decent BSFC where you'll manage significantly better then 10hp per lb/min...

83 Crossfire TA

iTrader: (2)

I'll answer your question if you tell me where you got your map…


VE depends on how well your combination is working. FWIW, I did a little math last night and a stock L98 (well, my stock L98) is at about 83% between 4400-5200 rpm, and significantly higher then that at it's torque peak.

I'm not following what you mean by At 15psi, 90* compressor inlet temp and 70% compressor efficiency you'll have 347* compressor outlet/intercooler inlet temps. If you meant 130* intercooler outlet temp you'd need a pretty unlikely, 85% intercooler efficiency to get the temps down that far, which would probably cause a significant pressure drop across the core which would mean that you'd actually have to feed it significantly more pressure to get your 15psi out and need an IC efficiency greater the 90% (just about impossible unless you're talking about an air/water intercooler with an ice bath).

That's great if you can manage to drive at 6000rpm all the time, but what happens when you're on the street, screwing around and at just about full boost but not WOT, the tranny shifts at say 5K rpm and you find yourself at 2500-3000rpm at 15psi, well on the wrong side of the surge line? For that matter, you'll only be at max efficiency at your redline/shiftpoint and below it everyplace else.

A smaller turbo would not only be at a higher efficiency most of the time, but it would spool better, be more responsive and have a much lower surge line, all making for a more drivable car.

Well, this brings me back to my original question… where did you get the map? I've never seen any published maps for anything bigger then the T76. Compressor maps are not just about size but shape… there are times that one compressor might not be "big enough" to feed an engine, but that a smaller one is because of a different map shape (for some good examples compare the T70/72/76, for a lot of applications the 70 or 72 will make more power then the 76, same deal with some of the T04's, they're all over the map, especially the T04b's)

What are you actually hoping to make HP wise?

87F383

So if i were considering his twin turbo kit in the next few months...by reading what I have read so far 2 T61's even with some form of intercooling are way to much for the street. I'd never be anywhere near efficient use of them? I'm building a 383/396 and plan to rev to 6500 as my redline. Help great turbo gods!!! Im absolutly confused now.

85TransAm406

iTrader: (1)

So you don't assume 100% VE when doing the lb/min requirements? Just trying to learn...

scottland

83, thanks for the help. this is exactly what i need.

i did quite a bit of research about 6 months ago, when i found a map for a t-88. i honestly can't say where, i saw the map posted above and it looks pretty close to right.

a website i was using for turbo math gave 130F as a reference for intercooler outlet tempuratures. What is a realistic Air/Air Intercooler outlet tempurature to use when calculating figures?

i understand that im not going to be driving at 6000 rpm, if you look at my last post i said that. I drive a manual so my tranny doesn't shift itself :-). But i do see what your saying.

as far as power output, 600 to the wheels on pump gas is my ultimate goal.

here is a T-76 compressor map im looking at right now, supplied by Innovative.

GT76


so, revising the math, assuming 85% VE and say, 208*F intercooler outlet temp (60% intercooler efficency) i get 67lbs/min at 6000rpm and 40@3600rpm, which is still well clear of the surge line.

so i guess a T-76 would better the combo listed.

thanks for the help, its greatly appreciated

JoBy

That depends on how you define VE.

1) If you define VE as the volume of air entering the air filter divided by the size of the engine, then you get over 100% VE during boost.

2) If you define VE as the volume of air passing the throttle divided by the size of the engine, then it is a different story. The air is more dense so 1 CFM at the air filter will be less than 1 CFM at the throttle. You have boost forcing the air in, but you also have higher exhaust pressure driving the turbine. The pressure differance between intake and exhaust might be the same as a NA engine and then the VE at the trottle vill be about the same.

You often use the NA engine VE in calculations because then you can use that to calculate the air flow att different boost, air temp and back pressure.

BBSDesigns

For those of you confussed or trying to understand what this conversation is all about, I recommend buying at your nearest book store: HPBooks; Turbochargers, by author Hugh Maclnnes. This is the ABC of turbocharging.

BigMike92Z

Coincidentally I picked this up the other day. Haven't read through much of it yet as I haven't had the time, but it seems so far to be a very informative read.

BBSDesigns

For those of you asking if it can be possible to turbocharge carburated cars, well yes it is possible. All what is needed is a pressure plenum or carb bonnet that replaces the existing air filter on the carb and connects to the outlet discharge of the turbo. The only problem is with the wastegate pipe of the turbo header which runs very close to where the mechanical fuel pump is located. This requires to delete the mechanical fuel pump and replace it with an electric fuel pump, which in the other hand is better for turbocharging.
Thank you

BBSDesigns

Very good book, isn't it?

83 Crossfire TA

iTrader: (2)

Well, lets see if I can cover everything (sorry BBS for stealing some of your thunder, but looks like you've inspired some "what if" around here):

You try to realistically estimate what the VE of the engine will be at that point. The thing that people don't take into account is that you may be at 85% VE at your shift point (say 6000rpm), but you may be right around 100% VE (or higher depending on your exhaust design and cam) at your torque peak at roughly half that. Most sites and info out there about this whole thing focus on smaller engines, where surge isn't really that big an issue since a smaller engine is less likely to have the exhaust entergy to spool a turbo down there, but that is not the case with a V8 and some newer designs.

[QUOTE]Originally posted by scottland
[B]a website i was using for turbo math gave 130F as a reference for intercooler outlet tempuratures. What is a realistic Air/Air Intercooler outlet tempurature to use when calculating figures?

That might be reasonable with less boost or with a REALLY LARGE intercooler but I'd be surprised if it was below 150-200* or so with what most people use, especially if you ran something like this on a road course or for back to back Ľ mile passes. Remember that as your intercooler heat echange efficiency goes up you'll loose more pressure across the core, so you'll have to start with more boost. I'd bet that you'd be hard pressed to find an air to air that will give you 15psi output at 130* that will fit in an f-body that will result in less then 3-5psi drop across the core. That means that you have to start all your "figuring" over with what your compressor will do at 18-20psi to get then numbers for 15psi at the engine (If you look at most compressor maps this is actually a good thing, in general, in the range that most gas engines use running higher boost allows you to use a slightly smaller compressor).

Take this as you will, but I'm looking to ultimately see in the 500-600hp range out of an L98 using a bastard, home brew, jy bits and pieces turbo that has a 65mm inducer. A T88 has roughly 215% the inlet cross-section that my little 65mm turbo does.

OK, this just brought up another issue that a lot of you may not realize. Outside the standard T04's… most of the T__ turbos are a mishmash of parts that assorted aftermarket companies stick together and give a label to. That map does not match the T76 map that I know has been previously mentioned, but I also know that there has been some shakeup WRT to what compressors are being used on the newer Innovative and other similar offerings…

I'd call those much more reasonable numbers and a more reasonable choice.

I think that I've posted similar musings before, but for this discussion it makes much more sense to just stick to NA VE's and if there is a debate just point out that the volume through the throttle body is still the same, the mass is just greater. If you want to have a debate, it would be more productive to argue about compressor maps rated in cfm vs lb/min (volume/min vs mass/min) since they do not actually translate and most published maps are actually accurate in a fairly small range.

that is about the only book on the subject that I've seen that isn't just plain full of crap. It probably helps that the guy is actually a patent holding engineer in the field, but I think that is also what scares some people off (If this just dissuaded someone from looking at it, consider that he shows some of the math involved, but also presents thing in simplified formulas and also in chart form, so you really don't need to know more then a little bit of algebra and how to read a chart to get real answers from it)

BBSDesigns

No stealing at all, I feel very happy the way people are reacting and concidering on turbocharging their V8's. All this information posted by everyone of you is very valuable and informative.





I completely agree with you, I found very few good books about turbocharging. I also use to read Turbo magazine years ago, but now is more show than tech.



"Is good to know that the roach(imports) era is about to pass away".
"Lets show those lawnmowers with turbo what a real engine can do with turbo also!!!"

V8's on top of the food chain!!!:hail:

83 Crossfire TA

iTrader: (2)

What I figured was that the more discussion the better for you.

I've got 2 or 3 issues that had some interesting stuff in it, mostly GN stuff but I remember one regal with a TT SBC that was pretty wild.

You know, I'm kinda glad that you're getting the feedback that you are. I hope that you're actually selling some kits. We've had multiple discussions like this before, some with a new vendor showing up with "I can do it for $xxx" and then disappearing when he checked out the hurdles.

I've considered doing something like you're doing myself but got kinda fed up with "we want everything for $500" responses. As a matter of fact, I thought that you'd get a kick out of how similar this pic of what's sitting in my garage right now is (no cold side plumbing yet):

JoBy

Also similar

83 Crossfire TA

iTrader: (2)

JoBy, mine is actually built to work with the same turbo that you're using, the one in my pic is roughly one size down (it's mostly parts from the biggest H1E which is identical to the HX40 but with a different compressor outlet), which externally is remarkably similar the larger HX's. I've got an HX50 and 55 sitting in my garage but I don't really see the point with a stock L98 (they are pretty close in size to a T88, no matter what I tried the L98 put it to the left of the surge line somewhere).

I actually had the majority of the work done about 2 months ago, but came up for emissions testing last week and pulled it off and put things back to stock. While waiting in line I noticed my cooling fans weren't working and it turned out that I had some wiring harness problems which I've spent the last couple of nights straightening out. Hopefully I'll get back to pulling the exhaust apart and finishing it up some time towards the end of next week (assuming nothing else turns up that needs my immediate attention).

FWIW, for the time being I'm considering modifying the SLP cold air intake in that pic to work with the turbo (it's got a 4" filter fitting but only 3.5" tubing, wouldn't be that hard to cast some custom 4" FG pieces)…

83 Crossfire TA

iTrader: (2)

Anyone besides me find it amusing that we're all messing with '87 TPI's (with the alternator on the passenger side)?

BigMike92Z

then i guess im bucking the trend. 92 here.

Guido

Mark, do you have any more photos of your headers??

FSTFBDY

iTrader: (33)

me too me too..

any pic's of anything yet.lol.

83 Crossfire TA

iTrader: (2)

Well, my camera was broken while I was making them but I was planning on taking some pics while I finish up. Like I said, I'm hoping to get back to it at the end of next week. I really didn't plan on posting anything until I get it running since I've managed to sell off everything that I've built before I managed to have fun with it so far and am getting kinda tired of that. I don't think I'll post any real pics of it until I've got the car actually rolling with it on it.

FWIW, I started with a set of stainless vette headers (just like the TT setup I did a while back) which I cutup and did something different with (If you can imagine, combine the BBS, JoBy's and Preston's setups and you'll get what I have, there was no intention to make them truly tubular headers but there was a lot of thought put into flow control), used a bunch of stainless 4th gen parts and an assortment of flanges (I'm still looking for a 4" v-band clamp for the down pipe). I'm not firmly decided on what I'm running on the driver's side. I've got some stainless 4th gen headers that fit, but my instinct is to either modify another set of 'vette headers or to use some LT1 manifolds to retain heat and better spool the turbo (It's got what would be considered a massive turbine side, but part of my point is to experiment with trying to get a hot/cold side ratio of better then 1.5:1, if I can get it in the 1:1-1.5:1 range I think eventually I'll be able to cam it like I would an NA engine). Right now the flange tacked on to the crossover is for the LT1 stuff (I've got an "extra" LT1 sitting in the garage that may get some forged parts and dumped into "the car" eventually, this is the car that was in the pretty bad accident/bent frame and it's just serving as a mule until I get a new body).

Z28ricer

iTrader: (2)

Who is the turbo actually from ? turbonetics ? If so, would there be any extra charge for a T66 since the T series seem to be all priced the same with the exception of the 76, and what exhaust side a/r does the kit include, any extra charge for the D port flange on the turbo header side ?

BBSDesigns

Hi TPI383, just to let you know that Iwas unable to start the twin turbo headers this Tuesday as I said to you before, I will definetly start them next week, I'll let you know.
BBSDesigns

BBSDesigns

Hi the turbo shown with the picture is a Turbonetics 62-1, but kits are offered with a Master Power T61 Turbocharger which is slightly bigger than the Turbonetics 62-1. This turbo has also a 360 degrees thrust bearing which is one of the most desirable things. P.84 tangential turbine housing, "V" band, 4" inlet, 2 1/2" discharge. I was a "turbonetics only" kind of guy, but I got the chance to compare both turbos and now I realize what marketing can do to a person. I include this turbos because they are less expensive, perfect for making a high quality turbo kit at an affordable price. As for the flanges I can make whatever you want, in fact I am going to sell them in do it yourself kit form. The single turbo do it yourselfer kit will include; one sbc exhaust 3/8" steel flange, one standard TO4 3/8" steel flange with square hole or round hole and one wastegate (Tial, Turbonetics, Innovative flange type) steel 3/8" flange. For those of you interested, let me know.
BermudezBrainStormigDesigns@hotmail.com
BBSDesigns

BLOWN85/TA

iTrader: (2)

Has anybody used or thinking about a GT40 turbo on a 350CI? I am considering it and sort of wanted feedback. Part #703457-1 or #452232-5 there is an optional 1.19 turbine housing.

Z28ricer

iTrader: (2)

Im more interested in the complete kit and not a DIY header, did you change anything when going to their 61 or would I be able to easily upgrade it to a turbonetics 66 or 70 later as a direct bolt in ?

BigMike92Z

keep me up to date on those too, please.

BigMike92Z

66 or 70 should bolt right on. they all use the same flange as far as i know. jus thave to make sure and order it with the tangential exhaust housing.

Z28ricer

iTrader: (2)

Im just wanting to make sure it wont cause me any trouble with the downpipe stubby that comes with the kit moving and me having to fab another.

BigMike92Z

i believe you can option the size of the outlet as well when ordering a kit.

BBSDesigns

You can choose what ever turbo you want; Turbonetics, Master Power, Holset, Innovative, etc... and at the size you want. I include the Master Power T61 turbo in the kit becuse it gives you more bang for the buck in the same turbo size than the other brands. It is a very good turbo with 360 thrust bearing bolted-on, instead of being hold on by pins as other turbo brands do, and it haves basically all the goodies other more named turbos have. Either way if you want a TO4B-T88 or perhaps a TV94 : , just let me know and I will tell you how much is the difference $$.
BBSDesigns

SpectreGTA91

I've been following these turbo kits for some time now on Ebay, and they're looking [retty damn good. I was planning on buying the new Banks Turbo kit, but after seeing these, I may just buy them from BBS Designs. These look really damn good! BBS, please check your PMs, I sent you some specific questions. Thanks!

WinnipegGTA

Hi do you reccomend any TPI intake mods before using your Turbo setup..Larger Runners, manifold, or larger Throttle Body?

WinnipegGTA

To run it at about 12 PSI or so would you recommed getting forged pistons..can i still keep my compression at 9.5:1 though incase i ever take the turbo off?

BBSDesigns

If you add larger runners, throttle body and manifold it would definitely make more horsepower than a stock intake, but is not necessary to turbocharge your car. If I would recommend a larger intake I would go with the Holley stealth ram, like the one in the project car. It is cheaper than the Accel and cheaper than buying larger runners, manifold, TB and plenum.

BigMike92Z

i doubt the motor would take the abuse of 12 psi too long with stock pistons/rods.

like bbs stated, going ot a larger intake setup would net you more power @ comparable boost. boost is nothing more than a measure of restriction, so if you get rid of the restriction you can make more power on less boost.

SpectreGTA91

How is that 450 HP attained? What boost level is needed and is that from a stock or modified motor? Thanks.

WinnipegGTA

Would some forged pistons and a set of pink rods work ok on 12psi of boost?

BigMike92Z

i have zero experience with "pink" rods. go with a nice set of forged rods and pistons, lower compression and that will allow you to attain higher boost levels safely.

WinnipegGTA

BigMike is there a certain brand you would go with on a modest budget. Im not cheap but im not rich. Anything to stay away from.. I was really planning for a P600b but this is cheaper.

WinnipegGTA

Just wondering the downpipe from the Turbo..or the part that connects to the exhaust..what size is it 4inch or 3 inch?

BLOWN85/TA

iTrader: (2)

3" I asked that myself.