dizwiz24

Just got done doing 5 dyno pulls at Big Shot Dyno in Tallmadge, OH.

I made 471 rwhp / 461 rwTQ. Air temp was 68F, altitude, 1400 feet. 93 octane BP gasoline, 50/50 meth/water injection set at 5 gallons per hour in low boost and 15 gallons per hour once in high boost.

This was on a Dyno Jet dyno by the way. Ill try to put some videos up here. They are neat because you hear the scream of the supercharger and the hiss of the blowoff valve.



I would have made more power, but seemed to be fighting a battle with the knock sensors. Try to add some more power by advancing timing and the knock sensor would retard timing way more than the timing you tried to add. So in the end, you would have been better off sticking with the lower timing to begin with that way you didnt have knock sensors dropping off timing by 5 degrees !

Ive tried asking around to find out what timing guys run w/ ltx superchargers, but havent gotten any good answers. It seems to be a real mystery and trial/error is the only way to find out what works best for each case.

Heres my last run where TTS Datamaster datalogs indicated knock retard of 5 degrees at 5000 RPM. See what it did to the power I was trying to make. I was on target to make the most power on this run and it got spoiled by knock sensor activitiy (I didnt hear any knock btw).



My boost curve hits like this:

3000 rpm: 5 psi
4000: 7.5 psi
5000: 10 psi
5500: 11.25 psi
<rev limiter set at 5700 rpm to prevent boost from getting too high!>

Ignition timing is something like this:

3200 rpm: 31 degrees at WOT (when stock MAP sensor maxes out at 100 kPa).
3600: 27
4000: 24
4500: 22
5000: 21
5500: 20

I think whats holding me back is knock sensor (need to determine if its false or real). Also, my heads are a big limiting issue. The only thing is I dont want to put expensive ported AFR heads on and have a stock bottom end failure ruin the heads, so I have to wait until I rebuild the whole thing before doing heads.

My mod list is below.

-stock bottom end LT1
-stock computer w/ moates ostrich adapter
-Tunerpro RT software with $DA2 definion file
-TTS Datamaster v351 to datalog
-160 thermostat
-NGK TR6 plugs gapped around .035
-MSD 6-BTM (though boost retard was turned entirely off).
-base tune (tweaked by me) from Greg @ blowerworks
-AEM UEGO wideband monitoring drivers side exhaust bank
-Racetronix 'hotwire' Walbro 255 l/hr pump in tank
-60 lb/hr injectors
-new fuel filter (ie. didnt want the risk of an old fuel filter causing any flow issues)
-P600B blower with 8 rib drive bracket made by Greg @ blowerworks
-ATI 6+8 superdamper keyed crank pulley (from greg @ blowerworks)
-Gaseous intercooling meth/water injection system (from greg @ blowerworks)
-Hotcam kit (218/228 .525/.525 w/ 1.6:1 roller rockers)
-TPIS 1 3/4" long tube headers
-Dynomax LT1 mufflers
-mildly (prob. crappily) ported lt1 heads
-AS&M monoblade TB
-lightweight aluminum fidanza flywheel
-SPEC stage 3+ clutch

intheboost

Nice numbers. That car must be a blast on the street.

What do SC'd LT1's put down without meth?

dizwiz24

I ran 440 rwHP / 442 rwTQ back in sept. 09 without meth. The timing ws being retarded down to 13 degrees (at some point) due to high inlet air temp (pcm retards timing based on inlet air tmp and knock sensor).

I also was running the restrictive procharger intercooler so that was costing me about 2 psi boost.

Ive now relocated my IAT so that it senses ambient air temp vs. supercharged (compressed inlet air temp).

Im running the meth/water purely for the anti-detonation characteristics since Im on a stock bottom end.

BrianCunningham

Nice flat torque curve, which some people say a centripetal blower can't do.

More of got more out of it with more lobe separation on the cam.

dizwiz24

Its the hotcam. I think 112 LSA?

The real issue is my crappily ported stock heads.

however, I dont want to invest in expensive aftermarket heads and have a stock bottom end failure ruin the heads.

Have you dyno'd yours yet? Also what do you do for your spark advance? (what is it set at? )

Some boosted LTx people will just run say.. 24 degrees at WOT from 3000 RPM andup.

Whereas I have mine starting real high...31 degrees at 3200 RPM and steadily backing down to 20 degrees at 5000 RPM in response to boost.

Im not realy sure what is best.

Theres just not a lot of information like that available for LTx hot-rodders.

djxib

Nice numbers - very similar to my old setup with the exception that I was using a Vortech S trim. I was able to run 30 degrees of advance at 6000 RPM spraying the alky, but I was also running on the rich side (some of black smoke at WOT). Not sure if it needed that much spark, but it didnt seem to hurt anything.

The torque curve was real nice and flat - a great daily driver and would cruise all day in 6th gear at 1500RPM.

I also relocated my IAT because it was causing inconsistency at the track and a hot-start problem. Best run at the track (on street tires and a very cautious launch) was 12.3 at 117.

Enjoy your car!

armysnipe

Are these numbers what you expected?

Has the larger throttle body made a difference (less rich or more power)?

I also have a tune from Greg. I am running about 26 degrees timing at 4000 RPM's and up. His initial tune for me was real conservative for my setup. At one time I was running the stock timing tables with 24LB injectors and an FMU. Greg was suprised I didn't do any damage by running lean. recently I switched to the WALBRO in tank pump, procharger booster pump and 63LB injectors. Big difference was my change in fuel pressure, but I'm sure you already knew that. Currently I have the stock crank, a forged bottom end, .30 over, 9.8 to 1 compression, the TPIS ZZ9 cam w/ 114 LSA, Edelbrock performer heads, air gap intake, IAT relocation and haven't noticed any timing being pulled. I'm sure my combination of parts helps. I chose the TPIS cam because it enables me to get the most flow for my setup. I'm also around 10PSI (smaller pulley) without meth but with the intercooler. Currently I'm doing some final tweaking with the PVC system and then will try and dyno. What areas are adjusted when dynoing? Also wondering, were your scans (HP/TQ) in datamaster close to your actual dyno runs, particularly the datamaster dyno tab. One day I'll take her to the track and get a time slip.

When you do your bottom end you wont be disappointed. My only regret is probably not going to a forged crank (weakest link). My problem is I did it at 70,000 miles and I probably should have waited. It's nice to know there's someone out there that loves thier C4 as much as me.

armysnipe

Are these numbers what you expected?

Has the larger throttle body made a difference (less rich or more power)?

I also have a tune from Greg. I am running about 26 degrees timing at 4000 RPM's and up. His initial tune for me was real conservative for my setup. At one time I was running the stock timing tables with 24LB injectors and an FMU. Greg was suprised I didn't do any damage by running lean. recently I switched to the WALBRO in tank pump, procharger booster pump and 63LB injectors. Big difference was my change in fuel pressure, but I'm sure you already knew that. Currently I have the stock crank, a forged bottom end, .30 over, 9.8 to 1 compression, the TPIS ZZ9 cam w/ 114 LSA, Edelbrock performer heads, air gap intake, IAT relocation and haven't noticed any timing being pulled. I'm sure my combination of parts helps. I chose the TPIS cam because it enables me to get the most flow for my setup. I'm also around 10PSI (smaller pulley) without meth but with the intercooler. Currently I'm doing some final tweaking with the PVC system and then will try and dyno. What areas are adjusted when dynoing? Also wondering, were your scans (HP/TQ) in datamaster close to your actual dyno runs, particularly the datamaster dyno tab. One day I'll take her to the track and get a time slip.

When you do your bottom end you wont be disappointed. My only regret is probably not going to a forged crank (weakest link). My problem is I did it at 70,000 miles and I probably should have waited. It's nice to know there's someone out there that loves thier C4 as much as me.

dizwiz24

30 degrees at wot seems wild. I remember hearing the old saying drop your total advance 1 degree for every psi of boost.

Though I don't know if that will change depending on if you have lowered compression or run alky/water injection.

Were you on a stock bottom end / stock compression with that kind of timing?

dizwiz24

I'm not sure if the larger tb added anything. Maybe if I had bigger heads on there and ran to higher rpm, it'd make a diff.

Honestly, these results were a little lower than what I expected. I was expecting 500 rwhp.

If I could have ran the thing up to higher rpm, without setting off knock sensor, then I think I could have gotten closer to my
goal.

I listened to my videos and couldn't hear anything special at that point my datamaster scans indicated 5 to 6 degrees of knock retard arounnd 5200 rpm.


I need to see if I have any metal rubbing. I think my header might contact the x brace and also the metal discharge tube (vortech) might touch the throttle body.

djxib

It was a stroked 350 (377 Ci) with forged pistons and large wall clearances (and hence a lot of oil consumption, although that's possibly not relevant).

BrianCunningham

I hoping to dyno it next week, just got the clutch broken in.

SloRvette (on the forum) did the engine build and is doing the tune.

PM him for details

LD85

Where do you hold the water/meth and how much?

Zix

Are/can you you running the LT4 knock sensor? It allows a bit more noise before stepping in on the timing.

5abivt

Have you datalogged on the street? Load tuning on a dyno jet isn't very accurate. Run too much timing and when you get out on the street you're going to blow up pistons. Good numbers though!

dizwiz24

I've got gregs (blowerworks system).

Low speed comeson at 2.5 psi boost. High speed comes on at 5.5 psi boost.

I wanna say its 15 gal/hr at high speed, but I might be incorrect.

dizwiz24

I don't think I can run that in my 93