Jeff20B

iTrader: (13)

I still believe in Camden's SCs. My friend's 7" had loose roll pin problem that Camden took care of. They replaced it under warranty and sent him a Holley 600 to replace the 390.

blown 83

bouis:

I respect your opinion about the supercharger. Hey, if you don't like, that is your choice. Get something else.

Just to clarify, because I couldn't tell if you were indicating that you think the supercharger had anything to do with my trashed motor, it simply had nothing to do with it. That motor was the absolute worse port job I have ever seen. Lines were all crooked, they were extended waaaay too far back. They were almost into the water jacket. That 13B was a timebomb waiting to explode.

To everyone:

I feel like the supercharger, as well as Atkins, is taking a bad rap here. That was never my intention. As far as the blower setup, it truly is in great shape. I figured this blower would be gone by now, but I know not everyone just has that kind of cash laying around.

If it was not for my good business relationship with Chris at Racing Beat, Atkins would always be my first call for rotary supplies. Thanks Atkins for your support.

Jeff20B:

Let me know if you hear from your buddy about the Weber carb or whatever he has (from the other board).

T.

bouis

I don't really have an opinion about the supercharger. I think it can be done right, and it's probably pretty darn kickass when it is. But, I have an opinion about Atkins and that sours the whole thing for me.

I'm sorry for dragging you into this personally. Obviously I don't know what caused your engine to fail, though I still don't think that running 10 PSI on a normal-compression engine is a good idea.

Jeff20B

iTrader: (13)

I told him about it yesterday. He didn't seem very interested. I'll talk to him again either today or tomorrow and remind him of the auction.

Rotortuner

Your looking at 200RWHP.
I saw dan atkinstry and run his on a dyno, it was a new engine, ported 13b 4 port. it did 176 RWHP and like 150 tourqueor mabe it was 175.
With my 13bt swapped fb, stock block emissions legal, 20 MPG, i put down 218RWHP and 245 tourque at 10psi. reliable.

CJG

Metallic_rock

That was only at 6 psi that Dan ran at, and I don't think that Dyno was reading right... too many people's stuff was WAY off what it should be.

Rotortuner

the dyno was reading right. HP is calulated streight from the drum, so the HP is a near perfect number. The tourque was off at first then they got that fixed, but like i said the hp was right on. i didnt see any bodys stuff way off, i just saw people lay down a lot less than they thought they had, i guess its just the difference between what people think they have and what they actually have. plus the rx8 put down exactly the same number within 5hp of what hundres of others have dynoed at.

CJG

Metallic_rock

I thought it was the other way around with the Torque/hp, cause the hp had to be calculated using the RPM, and they couldn't get a good RPM reading.

DriveFast7

iTrader: (1)

The 176 rwhp sounds like numbers a non-boosted car would put out.

I personally saw a 2nd gen streetported EP racecar only 1 muffler with weber sidedraft 38mm chokes put 186 to the ground, dynojet.

Rotortuner

No tourqe is a function of hp and RPM.
(horsepower x 5250)/rpm = foot-pounds(torque)

CJG

Rotortuner

ya i know, its sad, i have a freind and we have sheets for a really big street port 12a, off the header and that made 168 RWHP.

CJG

purple82

You can calculate one from the other, but the dyno is measuring torque.

Rotortuner

No the dyno does not measure torque, we used a dynojet, i large drum of known mass is accelerated. the hp is known immedietly then the tourque is calculated

http://mailman.xmission.com/pipermai...08/031042.html

you are right though, you can calculate one from the other, but in this case we knew exactly what the HP was, at first we were getting bogus torque numbere, because they werent getting good rpm reads, but then they got that taken care of.

Hades12

From your link

"Since HP is a calculation of the amount of work you can do over a period of time"



HP = work or force over time

Torque is a Force and has units LB/FT
HP is a number.

purple82

I stand corrected. I didn't realize there were time based dynos. These must not be as easy to tune on as you can't change load at a constant speed like you can with a torque dyno.

Rotortuner

from my link:
"a DynoJet reads how long it takes to accelerate a
known weight to calculate HP, then back calculates torque."

purple82

HP has units too. It's just part of the screwed up english system, but one HP = 550 ft-lbf/s.

Rotortuner

Yes these are the differences between most common engine brake dynos and most chasis dynos, i believe that most of the chasis dynos used in the auto performance industry are inertial dynos and most of the engine dynos are brake dynos, the engine brakes dynoes a lot of times used a water pump or generator and you can calculate load that way.
I have never actually tuned with either, but with the inertial dyno you just get the car on there and do a solid pull while your datalogging, i can see benefits to both.

purple82

Like I said, I didn't know some dynos used this method. On this type of dyno, you can't set an engine speed and vary load to tune an engine, you need to set a throttle position or load and let engine speed run up to get accurate readings.

Hades12

You are correct.


So it is a Force applyed over Time


1hp = the force needed to move 1 lb 1ft over 1 second.

so it is a measure of Force.

purple82

No, it's a measure of power.

Force is measured in pounds.

blown 83

Did I mention that there was a supercharger for sale on ebay.

http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMESE%3AIT

Just thought that I would throw that in there.

:-)

CODE BLUE 2

I found this information on another forum that had good info posted on the Atkins Supercharger kits, I know this guy and raced with him a few weeks ago so i know that he is telling the truth" He is also a forum member, his name is rotarydude.

Heres his quote:

These engines were originally built for specific RPM/HP/Torque numbers like generators, boats etc but this shows the numbers these can do and potential.

this is the worst one of the bunch
12a stock porting 7 inch supercharger 390cfm Marine holley

output 12lbs boost
max torque 156 ft/lbs @ 6700 rpm
max hp (flywheel) 225 @ 8000 rpm

13b 6port stock porting (86 NA rebuilt block)5 inch supercharger 390cfm Marine holley

output 11 pounds of boost
max torque 196 ft/lbs @ 5800 rpm
max (recorded) hp (flywheel) 264 @ 7600 rpm
test (target rpm was 7200) was concluded at 7600 rpm hp numbers had not peaked

13b 6port street port (based on 86 NA block) 7 inch supercharger 390cfm Marine holley

output 9 pounds of boost
max torque 178 ft/lbs @ 7200 rpm
max (recorded) hp (flywheel) 276 @ 9000 rpm
test concluded at 9000 rpm hp numbers had not peaked target rpm was 8500

Note that all of these engines were using "SMALL CARBS", all of these engines are fully capable of running past 8k rpms of course you don't want sustained runs past this but they can handle the occasional blast if it is a well built engine. I am currently using a 13b with a supercharger bought from a fellow forum memeber here is the info on it and what i am doing with it

http://www.mazdarepu.com/board/viewt...?FID=6&TID=821 orig thread

Remanufactured 13B - '86 type block with early front cover, S/C fitting in front cover. (stock porting)
New Wrapover manifold. (s/c manifold)
New Oil Pan & pickup - REPU pan.
New Waterpump and Housing.
New Complete Dual Electronic Ignition System.
New Holley 390 Carb. with Electric Choke, throttle bracket and clamp.
New K&N Air Filter and Housing.
New Air Filtering Lid.
New Special Clutch Kit Package: High Performance Clutch, Throw Out Bearing, Pilot Bearing, and Seal.


I put this into my 74 Rx4 never dynoed it it does not have anything special on the inside either it is a stock 86 type block. On the track i am currently doing 14s in the 1/4 mile with all of the stock drivetrain (no LSD) I am launching at 4000 and shifting about 9500 the only problem i have had is fuel delivery (need bigger fuel pump)

i hope that this helps and i will post other numbers as we get them

rotarydude

iTrader: (2)

sorry to be a newbie here the previous post was mine that was jacked from another forum

rotarydude (here) rotarydave (there) on the dyno pulls that atkins is getting info is flywheel engine brake type.... the one that Danny ran so crappy on was an inertia dyno..... these can be affected by other things ie the range tuning, the gear ratio how aggressive you get with it etc there was a rather large article on chassis dynos a few months back in Hot Rod magazine any one who wants more info should look it up i was really surprized at the differences that they noted between the 3 major types of chassis dynos it is good to note that the most common is the inertia type they are the least expensive easiest to setup and run as well.... the drawback they produce the lowest numbers but they are good to help tune a car completely through its rpm range

rotarydude

iTrader: (2)

ok now it is hammer time..... shut the hell up if you dont have experience with one of these superchargers...... if you have never driven one or even seen one of them in action then don't bash...... cause oh WOW you don't know.......... I have a simple Rx4 that has a base 86 engine with a 5 inch and have put 5000 hard miles on it over 100 of them on the drag strip launching at 4k shift at 10k the only problem i have had is i run so hard and spin so fast that after a couple of weekends of racing i have to replace the belt..... oh well heat does that kind of make rubber stretch a little

i am putting 11lbs of boost to my NA engine.... yes that is right NA not turbo.... no not even turbo rotors.


someone asked about fuel/fuel consumption, with the 390 i am running we fattened up made it really rich so it would not lean out, we also use manifold vaccume for the adjustment on the distributor i only use 91 octane or better just like a high boost turbo, i have run 14 s on pump gas...... i will say that until i made it rich and solved my fuel delivery problem and fixed the timing (all things my fault) it would ping when under heavy load over 6500rpm but the above things fixed that

last but not least......... Danny well what can i say I love him like a brother but several things come to mind number one that engine was replaced (should have been b4 the run) it had a spun rotor bearing.... amazingly the s/c covered for it and it still ran decent. second i am sorry but Danny does not know how to drive that car he gives me almost a 1k lbs and he has a LSD, also has 4.09s to my one wheel drive and 3.60 gears yet i am over a second faster in the 1/4..... like i have said before on an inertia dyno it is all about how you drive...... you try to ease into it and your numbers are crap