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Something different than you normally see
Posted: Wed Dec 01, 2004 6:59 pm
Run Date and Time: 12/1/2004 5:11:38 PM
Acceleration from 2500 to 7500RPM, interval = 500.00RPM
Absolute barometric pressure : 29.67 in.Hg.
Vapor pressure : 0.13 in.Hg.
Intake air temperature : 61.9 °F
Gear Ratio : 79.86 RPM/MPH
Correction Factor : NONE
TIME RPM POWER TORQUE
0.00 2500 57.1 119.9
1.04 3000 92.7 162.3
1.83 3500 144.6 216.9
2.40 4000 232.4 305.1
2.83 4500 309.8 361.5
3.22 5000 370.9 389.6
3.59 5500 421.3 402.3
3.96 6000 448.4 392.5
4.34 6500 469.1 379.0
4.74 7000 467.5 350.8
5.18 7500 458.1 320.8
That is uncorrected wheel HP by the way. SAE correction would drop the peak down to 455-60.
Didn't have anywhere to upload the graph to, so this is all I could do.
Anyway, thought some of you might find this different and interesting.
Others will close their minds and say RICE!
This is a turbo 4 cylinder Mitsubishi DOHC, bore is 86mm stroke is 100mm, 2.3L. Turbo is a 52 lb/min unit we make from a current Garrett BB cartridge. Car has all the goodies on it, aftermarket ECU etc.
Static comp ratio is ~9:1.
This is at 24 PSI boost falling off to 22 PSI at redline, on 93 octane pump fuel
. No water or alcohol injection, no tricks. I'm pretty sure I can get 500 wheel HP out of it on 93 pump gas, so far there is no detonation. It is not uncommon to be able to throw some serious boost pressure at one of these 'riceburners' and be able to get away with it on pump gas. You just have to be very very careful and sneak up on it.
Friday we'll throw the C16 and juice at it.
Posted: Thu Dec 02, 2004 3:44 pm
Well it ended up hitting 503 peak, should have hit 515-520, some weird shenanigans were going on between 6500-7200 RPM. Probably the odd tube length (12"-13") header and the high exhaust pressure. Played with the cam timing, gave it some more boost and it woke up.
Run Date and Time: 12/2/2004 1:05:54 PM
Acceleration from 2500 to 8000RPM, interval = 250.00RPM
Absolute barometric pressure : 29.70 in.Hg.
Vapor pressure : 0.16 in.Hg.
Intake air temperature : 63.6 °F
Gear Ratio : 79.91 RPM/MPH
Correction Factor : NONE
TIME RPM POWER TORQUE
0.00 2500 40.6 85.2
0.58 2750 72.3 138.1
1.08 3000 89.8 157.2
1.52 3250 110.3 178.2
1.90 3500 139.4 209.2
2.22 3750 178.7 250.3
2.49 4000 227.9 299.2
2.72 4250 274.8 339.6
2.93 4500 317.3 370.4
3.12 4750 350.6 387.6
3.30 5000 380.2 399.4
3.48 5250 409.6 409.7
3.66 5500 437.9 418.2
3.83 5750 464.7 424.4
4.01 6000 489.0 428.0
4.18 6250 498.9 419.2
4.36 6500 495.5 400.4
4.55 6750 486.5 378.5
4.74 7000 495.1 371.5
4.94 7250 494.2 358.0
5.15 7500 502.1 351.6
5.36 7750 490.4 332.4
5.59 8000 482.2 316.6
Posted: Thu Dec 02, 2004 10:41 pm
-have you done anything to the heads? changed cams, valves etc or is it a stock internal engine?
Posted: Fri Dec 03, 2004 9:27 am
bill jones wrote:-have you done anything to the heads? changed cams, valves etc or is it a stock internal engine?
Eagle H beams, custom Ross pistons, some mild head work. On the heads about the only reason we go +1mm is to be able cut a decent seat profile.
If you want Ferrea quality at a lower price look into Supertech for valves.
Not a lot of science in the ports, just basic cleanup. The intakes flow in the 280-300 CFM range @ 28"/H2O at .400-.450" lift, exhausts 240-260. Valves are 34mm intake, 30.5 exhaust. It just isn't cost effective to spend a bunch of time in the head when you can just crank the boost and slap a bigger turbo on it.
Intake manifold is a sheet metal unit, total runner length is ~ 8". Intake manifolding is pretty much an open market on these things, the ones on the market are crude and simple with very little real development. They all improve upper RPM power, but there are no real gems out there.
The cams are hydraulic end pivot rocker, .415/.400" lift and seat timing is 259/258 on 108/114 lobe centers.
I do spend a lot of time on the chambers because the factory castings have a buttload of shrinkage towards the outer cylinders and the chambers are offset a bit and very inconsistant.
No coatings. I'm not convinced thermal coatings help much after the base layer of carbon gets built up. I would like to do the exhaust ports, chambers and see if it helps on the very high HP apps where the head folds up like a potato chip under the exhaust port and blows the head gasket in 2 runs.
This particular engine showed some signs of 'magic', where it usually takes an NGK 8 or 9 heat range plug, this one wants 7's and has very little signs of knock activity.
FYI the timing it likes on pump gas at full load is 10 deg ramping up to 13 after 6000, and I usually run them in the 11.5:1 AFR range for pump gas at full boost. This one will tolerate 13:1 but it ain't worth the extra 10 HP.
Boost controller was not allowing full boost till 6000, should have full torque at 4500, and it drops 2 PSI from 6000-7000.
Posted: Sat Dec 04, 2004 12:22 am
-I heard this story by Gale Banks.
-Some guy asked him if and why you would need to do all the same work on a turbo engine that you'd do on a highly tuned naturally aspirated race engine.
-Gales reply was "if your engine's a dog and you put a turbo on it what do you have, just a turbocharged dog".
Posted: Sat Dec 04, 2004 12:56 am
There's a lot of truth to that in relation to the factory V-8 world, and older designs, but a lot of the modern product is so good from the factory (in relation to airflow, engineering/parts quality and overall efficiency) you don't need to do much to get good results.
All the same rules still apply, this setup hits .55 mach at ~8500 and power takes a dive. Piston speed is thru the roof too.
Right from the factory the discharge coefficient is very close to ideal.
Posted: Sat Dec 04, 2004 1:36 am
-I do a lot of heads and some of the block sleeving for Subarus for a friend in the mid west, and we have been buying our valves from Willy at Supertech and we have Regis at Tick Titanium do our retainers 1000 at a time.
-It's an entire different world doing these 4 valve heads because you have to build all your tools, set up all your flowbench tooling, and for me learning the metrics.
-One of the biggest issues I face is the limited depth that the valves can be moved towards the cams because of the lightweight solid lifter arrangement we are using.
-I've had to make special cutters for spring pockets, make special spring shims for our choices of valve springs, jigs for welding in the extra injector nozzles into the manifold, special adaption so we can get the big throttle bodies onto the manifolds, fabricate the large fuel rails, and I have made special fixturing so I can set up accurate valve lash on the solid tappets without having to have the cam installed.
-But it's neat to be involved in it.
-What do you do about valve spring pressures, are your intake versus the exhaust the same pressures or do you compensate the intake for the blowert boost?
Posted: Sat Dec 04, 2004 2:50 pm
Generally don't see misfires or power loss from valve spring pressure (at any boost) until they get lower than 40 lbs on the seat, and then only at higher RPMs. Factory springs are 66 lbs on the seat and well under 200 over the nose and are good for 8500 on mild cams. We usually hit 80-90 on the seat and 240-250 over the nose and they are good for 10000 RPM with the occasional misshift and 12000.
I'd like to try some faster ramp rates but the base circle is so small (1.15") so far I haven't found any cam companies that can cut a fast ramp rate due to cutter/grinder wheel diameter.
About the worst thing that happens when the springs go soft and the valves bounce or float is it will spit the rockers out. They are a roller, rail type guided by the stem on one end and a hydraulic lash adjuster with a pushrod type end on the other. Attempts at converting to solids have been less than successful, the area of the casting the lash adjuster sits in is 'free floating' so to speak and moves around so much with heat and load you can't maintain lash. Lifter pump up on the hydraulics can be an issue if you have too much oil pressure in the head.
Of course the most expensive springs out there for this application (Ferrea) are the worst ones, they sack out in no time, waste of money.
Posted: Sun Dec 05, 2004 2:45 pm
-Is this a front wheel drive or rear wheel drive?
-Have you measured the absolute pressure inside the manifold and/or the internal manifold temperature during the dyno runs?
-If you did what numbers do you see?
Posted: Mon Dec 06, 2004 2:24 am
It is an all wheel drive. For chassis dynoing we use a locked center differential (either welded or a locking mechanism is temporarily installed) and run it in FWD mode.
Whch manifold absolute pressure?
On the intake it would be ~14.7 + 26 = 40.7 PSI, and 85-90 F. IAT's are 75-80 F at the throttle body during the runs on a hot engine in 62F ambient.
Posted: Mon Dec 06, 2004 4:34 pm
-I was just wondering if you reading a boost gauge and adding that to your sealevel baseline or getting data from a computer or actually measuring the absolute air pressure.
-I have some old mechanical absolute pressure gauges that one reads in inches of mercury absolute, and another reads in psi absolute, and they both have scales high enough to read the boost pressure you stated.
-What do you use for axles?
-You must be using a 2 wheel drive dyno?
Posted: Tue Dec 07, 2004 9:30 am
Posted: Tue Jan 11, 2005 2:47 am
Supertech valve's ??? never heard of ?
Posted: Tue Jan 11, 2005 6:45 am
See if these peaple have a spring that will work