Confuzed1

iTrader: (4)

Of course I didn't get the numbers I was hoping for, but they say the dyno is a great "reality checker".

I had 2 runs on a Mustang chassis dyno. Let me tell you, blowers sound wicked when the throttle is opened on the dyno. The blower whine is almost deafening!

The first run was cut short due to detonation around 4800 RPM's. So it only recorded from 2595 to 5300 RPM's. Results were:

Max Torque (Ft-Lb) = 465
Max Power (HP) = 362

-HP and TQ average did not calculate due to detonation. Max AFR was 15.3, Min was 10.0 - average = 12.4

The tech said he likes to see 11:1 AFR on a blown engine, so he went up 2 jet sizes on both primaries and secondaries and backed off the max timing (it was too high at 40 degrees) -Now set at 12 initial and 28 total.

2nd run was recorded from 2547 to 5916 RPM's and results were:
Max Torque (Ft-Lb) = 492
Max Power (HP) = 375
Max boost = 5.7 PSI

Average Torque = 421
Average Power = 342

AFR stayed pretty much at 11:1 the entire run.

-I guess on a good note, torque never dropped below 400 until I reached around 5000 rpms, and HP peaks at around 5100 rpms.

I was hoping for a bit over 400 HP to the rear wheels....somehow I knew torque would be high. When it was N/A, it engine dynoed at 390 HP and 490 TQ.

There's a couple of things I know of I could do to improve the numbers a little I think. I'm still running a CAT on the car, which I plan to remove. The carb might be a bit undersized too (650 Demon).

I also plan to change blower drive pulleys down to the smallest they offer, which should give me around 6.5 - 7.0 pounds of boost. Only way I could get any more boost after that is to change blowers.

I guess overall, I'm not too terribly disappointed.....it's runs seriously strong, and if I take care of some traction issues, I think it could run 11's at the track possibly (or so I'm told).

Not sure how the power I'm making at the wheels translates to FWHP, but I'm hoping that if I make a couple of the changes above, I might be able to push it to over 400 RWHP - maybe. What do you guys think?

Rolling Thunder

Well Personally i would be expecting a bit more than that. If this is the car your talking about is the one in your sig a 400 ci SBC with FI should put out a good bit more than that. usually they say its like a 20% loss in the trans that puts you at about 450 or so which is achievable on a hot NA 400 even 350s (though not with the same drive-ability and low end grunt). The torque looks pretty good but even that ide expect a little more out of a FI 400. Just doing alittle quick math your old hp rating at the flywheel was 390 hp drop 20 for the trans that means you were at about 310 with a FI system they claim you should gain about 30-50% which would put you at about 430 hp at the wheels which leave like 60 hp unaccounted for. Granted thats just alot of rule of thumb psudo-science math but it demonstrated what im trying to say. you might want to post the specs of your build but i think right off the bat the 650 seems like its would be a bit on the small side for that type of displacement as you already know. Also the exhaust even with no cat (although ide bet it would help quite a bit) i still think would be hurting you. Im not FI expert by no means but post your specs and ill do what i can to advise and by then probably some more knowledgeable members on the subject will post there opinions as well.

Confuzed1

iTrader: (4)

Thanks for the reply Rolling Thunder!

Yeah, as I said, I was expecting more on the HP side...but I also realize I'm not set up optimal - yet. The 390 HP was when the engine was NA, and that was engine FWHP.

Now, with 5 pounds of boost, I'm getting what amounts to 450 FWHP and 590.4 FW Torque. - in theory.

So - if I'm supposed to get at least a 30% increase with a blower, I could just add: 390 NA FWHP, minus 20% driveline loss = 312 RWHP.

A 30% increase of 312 RWHP would be 405.6 RWHP. Since I'm only putting out 375 RWHP, I'm missing 30 HP at the very least.

I think more timing could have been put in it as it is now, and I would have gotten more power. We stopped the testing short because I decided to go with a larger carb, another pound or two of boost, and ditching the CAT. I'll dyno it again after that to see where I stand.

I'm sure LT headers and true dual exhaust could help, but it's just too much of a hassle on these cars. I'd give up massive ground clearance. So the single 3" exhaust needs to stay.....unless I can find some shorty headers with 1.75" primaries and maybe a Spintech 4" catback.

I have a 750 Pro-Systems Holley sitting in the garage, but the power valve is not manifold referenced as it should be for blower use. I found that Demon carbs are easier to adapt for blower use by just buying a blower specific baseplate.

Supervisor42

Can you post the graph and cam specs?

NY87Iroc

iTrader: (1)

If it was mine I would def get rid of the cat and go with a bigger carb!..Both are restrictions

Rolling Thunder

Yea it is a pain to try and run duals but even a factory routed system can work as some companies make 3.5" and even 4" cat backs! The next thing ide be curious is the cam being that it was designed for na set up and switched to fi i bet by swapping the cam we could pick up quite a few hp there. Also what heads are you running?

Confuzed1

iTrader: (4)

Lemme see if I can attach the graph...

Confuzed1

iTrader: (4)

Supervisor42 - I'm running a retro hydralic roller cam from Comp Cams, recommended by their techs. It's a NX276HR cam, "Hydraulic Roller-Street Machine with 125+ Nitrous system or small supercharger. 2200 stall with lower gears" Duration @ .050 is 224/236, Lift is .502/.520, 113 LSA. RPM range 2000-6000 rpm's.

- Dart Iron Eagle 200cc intake runners, 72cc chambers
- 9.1:1 compression
- All forged internals/pistons
- Ford 9" W/Detroit Tru-Trac, 3.70:1 gears,
- G Force 5 speed
- MSD boost retard box
- Accel pro-billet distributor w/Hyfire coil
- 650 DP Speed Demon carb - with PV referenced baseplate
- Edelbrock TES headers, 1-5/8 primaries
- Hooker catback 3" dia. exhaust w/cat
- Traction currently sucks

Supervisor42

I'm amazed that you got over 400 FWHP out of a 650 carb. Is this a "blow-thru" setup? Also what kind of gas were you running?

Confuzed1

iTrader: (4)

Well, I'm certain 375 RWHP would add up to more than 400 FWHP on an engine dyno. I'm running a semi-helical screw blower in a draw though application. I was running 92 octane premium unleaded from BP at the time...

Supervisor42

I would change the carb before I ditched the cat. With a blown 400+ ci, a 750 may not be big enough to provide max hp that the setup can make...
EDIT: also I wouldn't go higher on the boost pressure with 9:1 C/R, you would would just have to back the timing down more negating any benefit.

Confuzed1

iTrader: (4)

Well, you may be right about going to a bigger carb since the blower kit I got could be ordered with or without a carb.

When you order it with a carb, it comes with an Edelbrock 800 cfm vacuum secondary. - I just couldn't bring myself to switch to an Edelbrock carb since I've had issues with them in the past.

As I mentioned earlier in the post, I have a Pro-Systems 750 carb sitting around that's been flow tested to 790 cfm's. I'll need to manifold reference the power valve to make it work properly though with the blower. In theory it should breathe better I guess. The CAT will come out either way...I have no smog or inspections to worry about and it's not my daily driver by any means.

The engine compression is exactly where the Magnuson recommended using this blower. Since it will max out at 7 PSI on my 400, any detonation should be easily controlled. My only issue is i can't hear if it is detonating (unless it's severe) , so I need to dyno it to find out.

I guess I'm only hoping for a little over 400 RWHP out of my setup......they advertised this particular blower to put out 507 FWHP on a ZZ4 350 - But I realize engine dynos are "ideal conditions" i.e. no restrictive exhaust, optimal cooling, no acessories etc..

So does everyone else feel like a bigger carb will give me that exrta 25-30 RWHP I need to break the 400 mark??

Supervisor42

Ahmen on the Edelbrock. They are cheap junk. Your engine deserves better.
You are dead on with using the dyno to get the A/F right. This is the important part most people skip. You'll have to schedule another date with the Mustang to dial in the 750.As I said before, I can't believe you made as much as you did with the 650. Don't forget, with the bigger carb, the boost pressure will be higher.
EDIT: (and post a video of the blower singing!)

NY87Iroc

iTrader: (1)

The more air and fuel in + the more air and fuel out = more power!!! If it was me I would have atleast a 850 double pumper on it and get rid of the cat!

Confuzed1

iTrader: (4)

Really? You think the 650 is resticting it that much?? - I mean enough to see extra boost on the gage?? Either way, both you and NY87Iroc convinced me...I'll get the 750 set up to go on and see what it'll dyno at then. I'll also try and get a vid next time it's on the dyno.....you can't hear anything but the blower screaming in the whole building!

EDIT: I also installed the smallest pulley I can run with the blower (2.8") , so hopefully I'll see around 7 pounds of boost this time around....

anesthes

iTrader: (12)

Funny how you replied to my 400 boost thread and while searching I found this one.

I was hoping based on your combo to see some mean 600hp numbers.. Something is wrong here.

For example, I had an old combo a few years back:

355
9:1 compression
Crappy Iron sportsman II heads - way worse than yours
S-trim blower
Singleplane manifold
224/230 @.050 cam, .502/.510 lift, 112 lsa

Car ran 119-120mph trap speeds, at 3650 lbs race weight.

Play with calculators and all that, that's nearly 480 rwhp.

I would expect a motor that has 50 or so more cubic inches and way better heads to spank it. And spank it hard at that!

I don't know if it's the 650 cfm carb doing it, but I'd start there. I ran a 75MM throttle body on mine, which is around 1,000 cfm of airflow - S-trim blower is rated at about 720cfm at the impeller speed I was turning, so I'd think you would want to run at least a 750 CFM carb.

-- Joe

Rolling Thunder

Actually i think you could go with a little larger carb than 750. Reason being you can calculate how many CFMs you will require in your worst case scenario so to speak. The formula, CFM = (displacement x rpm)/3,456*VE% shows the relation ship of RPM displacement and volumetric efficiency. Crunching through the numbers CFM = (400ci * 5500 RPMs)/3456 *1.3 = 827 CFM. Now this is a conservative calculation of the max CFM you would need assuming a conservative max RPM of 5.5k RPMs. How i derived the VE is because your running boost theoretically at 7 pounds boost that's roughly would equate to a possible 150% VE. Realistically it will most likely be less than that and your not running 7psi of boost all the time anyways so i kicked it back a little to 130% (again concervative estimation based on roughly 4 pounds of boost and a free flowing intake and heads). You can see even at this conservative calculation i came out to be around 827. So although you could run a 750 CFM carb and it would have great drive ability, torque, and throttle response (as your motor does now) i think you would still be leaving some HP on the table (as your motor also is now). What you place emphasis on is up to you its just something to consider before buying a carb.

Confuzed1

iTrader: (4)

Ha ha...I wouldn't of replied to your thread if I didn't have at least a little experience with a roots type blower!

I know there's more power to be had with the small blower I have, but I don't think a real comparison can be made between a S-trim centrifugal blower and any roots type, can it?? I'd think where the power is made between the two is different - you didn't mention how much boost was involved on your 355 either. Centrifugal boost increases with rpm's right?

Either way, I totally agree...It should be making more. But, it was only 5 pounds of boost at the time. I think I could give it more timing advance pretty safely, since the guy on the dyno went from 40 degrees total advance and decreased it to 32 without trying to find a happy medium. Most likely the reason he didn't is because after I saw the numbers, I told him I'd increase the boost and dyno it again in a month or so. I don't think he was trying to tune it per se, he just got the A/F ratio and timing in a safe zone for me to run it as is.....honestly, all the people at the shop at the time were more impressed with it than I was.

But as I said earlier in this post, they advertised this particular blower to put out 507 HP on a ZZ4 350 with 8 psi of boost...on an engine dyno. On a 400ish cube motor - with the smallest pulley they sell for the blower, I'm only seeing 6.5 to 7 pounds now. I can only tune to get more...increasing boost would involve a different blower....I'm maxed out on boost this thing can make by going to the smallest pulley after the dyno.

If I got 480 RWHP from this blower, I'd be very happy with it and call it a day....now, if I add 1.5 to 2 pounds of boost, get rid of the 650 carb and put on a 850 cfm carb and get rid of my CAT will I see a 105 HP increase at the rear wheels?? I'm kinda doubting it, but we'll see!!

-Rolling Thunder: Thanks for doing the calculations, I'm lousy at that stuff...

I guess I want the best of both worlds, I don't want to lose the throttle response it has now, but be able to use whatever this blower will give me.

Saabster

iTrader: (2)

8 psi on a 350 should be around 7 psi on a 400.

Something is definitely not right with this setup, that torque curve is dying waaaay too early. Is the boost staying constant as the RPMs build or does it start to fall?

rx8ss

Oops, did not know set up was draw-thru. Can't see any pics at work due to firewalls.

Supervisor42

RTT. It's a draw-thru setup. The best blower in the world is only going to "draw-thru" 650 CFM from a 650 CFM carb.

anesthes

iTrader: (12)

Here is some numbers I've been playing with:

Inch per rev Foot per rev RPM CFM @ RPM
177 0.102430556 6000 614.5833336
144 0.083333333 6000 500.0000003
142 0.082175926 6000 493.0555558

This should be a rough conversion for ratings on the blower to CFM.

Blower like the Vortech are rated at CFM @ max efficient impeller speed, which happens to be 720cfm for the S-trim.


To answer previous questions, My S-trim would make around 12lbs of boost on a 9:1 355 motor.

Carb sizing is an interesting topic. A 400 at 6,000 RPM, at 100% VE requires a 694cfm carb.

With that said, at 102% efficiency at around 5k (calculators) we're at about a 708cfm carb.


I don't know.. I'd probably run a 750CFM carb naturally aspirated, so I don't see why a 650 would work with a blower.. Just seems to small.

-- Joe

customblackbird

iTrader: (15)

forced induction has a funny way of covering up poor flowing heads etc... which is why i would assume he made that much power with a 650 carb... pushing air though something like carb/heads with a blower changes the characteristics of the design. i would def increase the carb to a 750 or a 850 and see how it helps. u should gain a good bit of HP wit that alone but the exhaust will restrict u prob even more once u increase induction and fuel.

next thing thats killing ur HP is your exhaust. those edelbrock TES headers are poop, i have them on my 86 TA with a 305tpi and they are barely enough for that, i wouldnt even stick them on my stock 87 formula 350tpi... which i put true 3" duals with xpipe and LT headmans. the edelbrocks have a 1 5/8 primary... which is almost too small for a 383 let alone a 400. a healthy 450-500hp 383 would require 1 7/8" primary LT headers... your 400 should work well with the 1 7/8" long tube headers. also the edelbrock headers have a 2.5" collector... that is SQUEEZED to fit, this cuts the primaries down even more! like 25%! a good 3" collector will help u ALOT! and a good true dual 2.5"/3" system would make GOBS of more power. remember turbos need huge exit exhaust sizes due to more air/fuel in the combustion chambers. i would say a 3" true dual system with 1 7/8" long tube headers would net u at least 25rwhp easily. You could go the more $$ way and look for a header with 1 7/8 primaries and a 3.5-4" Ypipe and then ditch the CAT and run a 3.5"-4" catback but thats gona be a bit of coin.

i would swap the to smallest pulley... for 7psi or so, and upgrade the carb to a 750/850 and do the exhaust(ditch cat too). i can gaurentee you would have way over 400rwhp. to me those seem to be the things holding you back. once u take care of the air and fuel goin in... u gotta get it out. You got a bottle neck at the front and rear of the engine. im surprised u got that much outa it.

also auto trans usually looses 20-24% with drivetrain loss, manual trans looses 18-20%

Confuzed1

iTrader: (4)

Thx for the replies customblackbird, anesthes, Supervisor42, Saabster....

I'm deciding whether I want to modify my exisitng Pro-Systems 750 carb so the power valve is manifold referenced, or just bite the bullet again and buy a new 850 Speed Demon supercharger carb and just sell the Pro-Systems and my 650 Demon carb on ebay or something.

To answer a few questions, the boost stayed pretty much constant at 5.3-5.4 pounds of boost during the entire run. As mentioned earlier in the OP, I since changed the drive pulley so I *should* be getting around 7 pounds of boost now.

I plan to switch to a bigger carb, ditch the CAT and see what I'll pull on the dyno with the extra boost and those changes alone. If I still get low numbers, I'll need to look for any other bottlenecks...I guess I just need to see what happens.

I know the TES headers aren't the best, but at least I have the HO version that dumps into a 3" exhaust. I agree that bigger primaries should help it though.

anesthes

iTrader: (12)

TES headers are not the best, but all I ever ran on my thirdgens was hedman 1 5/8" headers and you know how well that motor ran.. I think the problem is on the intake side if anything (carb, air cleaner, etc).

Honestly, the thing should fly. Though reading some data on the car I'm not 100% convinced the blower is big enough, but still, you should be seeing some serious numbers.

The charts seem to imply that at 12000 RPM (top pulley speed) that is about the fastest efficient point, the supercharger has an inlet
flow of just under 700cfm.

My math says at 12000 RPM 847CFM. Odd. Is the M122 122 cubic inches of air per rev?

That is a pretty outstanding RPM, considering. A 140% overdrive ratio on a weiand 177 at 6,000 engine RPM is 8400 blower RPM (840cfm).


-- Joe

Confuzed1

iTrader: (4)

Since the air cleaner was off and the hood was open during the dyno runs, the only restriction left is the carb on the intake side.

I don't think Magnuson rates thier blower CFM like Weiand does. It's not a traditional roots type. It's a semi-helix design. Some of the more $$ models also have intercoolers, and they've advertised huge numbers on other engines. Do a search on Magnuson, MP-122 and it'll tell you more.

Oddly enough, the car actually does fly right now...if I could get some traction it would be even better! It's just the dyno numbers that aren't adding up...there's more power somewhere.

anesthes

iTrader: (12)

Sorry I missed that.

Yeah I did, that's how I got some of the intel.

Weiand, B&M, they rate the blowers in cubic inches of air per revolution.
So you do a calculation to convert it to CFM, then you figure out the blower RPM based on pulley sizes and engine RPM. I always calculate things out at 6,000 engine RPM because that's about where most street cars shift, give or take.

So for example, a weiand 177 at 6,000 engine RPM with an 'appropriate' pulley ratio would be at 8400 blower RPM, which is 860 cfm.

So in theory, more CFM than a Vortech S-trim, however, the efficiency is like 40-50% vs 70s for a centrifigul blower. Your putting more heat into the charge.


Now your blower is more efficient, however the efficiency numbers are not released by the manufacturer, so we really can't build a direct comparison. What the MFG does release is the CFM, which seems absurdly low for the RPM, and the HP required to spin the blower, which happens to be 50hp at 12000 blower RPM. (a number I arrived at based on their charts).


I'm sure it is fast. I just think it should be faster.

I need to read more on the blower. I've had most of my experience with centrifiguls to begin with, but beyond that I'm having a tough time finding reliable data on the M122. The charts and data don't really give you any comparison because nobody rates their blowers that way, only they do.


-- Joe