First, if this is a street car or a race car with multiple stages I’d suggest that you get some sort of box to retard the timing with the activation of the spray.

Second, if you’re really running a 300hp shot I would hope that you have some clue on tuning already, if not then I would suggest starting with 100hp and work your way up about 50hp at a time. Detonation with a power adder is deadly… don’t go there period. Big hits of spray start doing strange things in that range, it is nowhere near as simple as jetting up at the same n2o/fuel ratio.

Lastly, timing has to be retarded when spraying because N2O is more O rich then air, so you get a faster burning charge. Remember, burn rate is not related to octane number. The engine does not require more octane as much as it requires less timing. More octane will not change that fact. Retard the timing or you’ll break ****. The reason that race gas is a good idea with N2O is that you don’t want any chance of detonation, and it is the easiest way of guaranteeing that, especially with skyrocketing cylinder pressures with big hits of spray. FWIW, N2O so effects the timing of the ignition of the charge that in most cases even with a little spray you can retard total timing as much as 8 or more degrees with no loss of power.

 

Sometimes I don't give enough information for a good answer.

Yes, I have a digital 6+ which allows 9.9* of retard. I'm also running a progressive controller. The car has seen 150 shot on the old build up for a couple of years. I'm just new to the separate fuel system deal.

I figured by using race fuel w/ higher octane it would make up for the ~2* that I still needed and be a good idea w/ a big shot.

 

That _probably_ doesn’t change my advice (probably because like I already mentioned, big shots aren’t always 100% predictable)… in general, race gas in that app isn’t a bad idea, but it will not let you run significantly more timing and a few deg difference in timing will make almost no difference in power output when spraying

 

This is slightly off topic but I promise I'll explain "Jet fuel" to a full extent.

I'm currently doing an internship at Pratt in their engine overhaul facility in central West Virginia. The engine you were running in the citation was a PWJT15D. They are one of the older turbine engines that pratt sold. They actually have an adjustment **** on the engine that allows you to run different density of fuels in a pinch. These engines meter fuel mechanically so you have to adjust for density manually. Jet engines are very sensitive to density mostly because of the range of altidude they fly at. Jet fuel and jet engines are alot like diesel engines. Since fuel is injected right into the combustion chamber there is no need to have a fuel with a high octane number (knock resistance) so they actually make more power with the lower octane jet fuel. Thats why they can run the 110 AV gas and get away with it, but the engine does need to be compensated for the different densities of fuel.

As for the price of a rebuild 250,000$ is dirt cheap. Most rebuilds run around 500,000$ and up, much more for the newer PW305/306B engines in the larger jets. Just the fan, the blades you see in the front of the engine run you 110,000. You should see an engine thats had a canadian goose ran through it. Almost every blade needs replaced, and there are 7 sets including the fan! As for installing one in your camaro, I'm already planing. Prat makes what they call a turbo prop which is a jet engine that turns a prop. Which could easily be hooked up to a tranny. They make between 500 and 2000 hp and are about the size of a big block. Actually the jet car that entered the indy 500 years ago was running a Pratt PT6 turbo prop, unfortunatly they are now banned because they were leading the field by like 20 laps when they broke.

 

The price I was talking was for an engine that was damaged due to a hot start, now that I recall. I think only one or two sets of blades were cracked.

Yeah, the PT6A's a very cool, and I am looking forward to the approval of an STC that will allow installation of a small, lightweight 235hp turbo prop motor onto planes like the Piper Cherokee Six, Lance, Saratoga, and others. I don't recall the maker, it wasn't Pratt, GE or Williams. Maybe it was williams - I forget. I think I saw it in APOA Pilot, I'll go back a few months and look.

If you ever do a project turbo prop, I would love to hear about it. That was be simply amazing - the best of both worlds (flying and driving) in one!

Now, if only there was an STC for mounting the chassis of a stripped down third gen into the fuselage of, say, a P210 or something with a high useful load and THEN bolting on a nice PT6A!

 

heh. there are several turbine powered gokarts out there


a few of my favorate ones, are turboprop style... where the jet engine is basicly turning a fan.. this fan is connected to the drivetrain... so it can stop (like a torque converter) but its also a more direct connection then just plain thrust... making it faster.

my fav part is the fact that you get over 400hp and over 375ftlbs of torque, from a engine that weights about 10lbs more then a briggs and stratton motor.. lol.


fun stuff.

 

After spending a summer with these engines it makes me wounder why piston engines are so far behind the technology curve. Heck these things were using ceramic coatings back in the 60's. There are so much better materials out there to make parts out of, I guess price is a pretty big reason why most of us never hear about it and why John Force winces when he blows up a motor.

 

The turbine engines are great, but they are priced out of reach for nearly every "amateur" pilot out there. Going price for the smallest turbo prop used plane out there is in the several hundred thousand $ range. All those .0001 toleranced parts add up very quickly. In kitplane land, the LS1's are getting popular for some of the larger amphibians, along with the Subaru boxer engine (light, cheap, reliable). Light diesels are making progress too... Now back to your regularly schedualled programming...

Maybe we should start a thirdgen.org aviation board?

Andris

 

:werd: I miss working at raytheon over at TIA. and Cessna In orlando

 

I forgot to mention the REALLY cool part about the engine I was talking about (235 shp turbo prop) - the manufacturer list price is $38,000. I can't recall about the prop (I'm sure it's a three blade constant speed, and that it's probably $10k more).

 

I realize that a few deg. won't be a big deal on the jug. But I want to try and keep as much power as I can when I'm running on motor.

So your advice is to just pull additional timing out through the ECM and deal w/ it?

 

Oh yeah, I forgot, this isn't an turbine engine board...

 

I don’t get it, I must be missing something. You said that you had a means of retarding it through your ignition box… why not just wire it so you only get retard with the spray activated?

 

As explained in previous posts, the box only gives me 9.9* of retard. Not the 12 that is "required for a 300 shot (2* for every 50hp). So I need an ADDITIONAL ~2*.

 

I was thinking of an Airesearch M180-T serries 7 I think is the engine number gas trubine.
These things are tough, brand new they run about $110,000.
The compressors are a 2 stage centrifugal-type with raidal outward flow impellers.
The turbine wheel is a radial inward-flow type. With a duel entry first stage with cross over ducts to 2nd. stage single-entry open face impeller.
It max speed is 42,100rpms (100%) it has a gear box that reduces the shaft speed to 6,000rpms for 400Hz alternator and other accessorys, it could be adapted to a clutch if a thrust bearing and fly wheel were on there.
I know I have seen one at least of these on a boat, it was heavly modified but I know that combustor can cap and torus any where.
You can play with the crack pressure to get to engine to idel as low as 10% or 4,210rpm shaft speed.
It is air pressure and mechanicaly controaled on start up and eletricly controaled during normal operation at 100%.
The engines shiping weight is 330lb, crate weighs about 100lbs.
I think it puts out about as much 700hp.
These are tough engines, they laugh at hot starts, bad fuel makes a little smoke.
There normal fuel is good old JP8, and will burn just about any thing as fuel.
Most appications you start the engine and it goes to from 0 to 100% in less than 10 seconds. No warm up.
When you shut them down they are at 100% and you just flip the switch to off. There are no engine controals.
They suck up dirt, no problem. I have startred them many times and the batterys have had just enough power to turn the engine just fast enough to get it to fire and it goes to 42,100rpms like nothing.
Some times they catch on fire around the exhaust, no harm.
They have a hard life and most of them last well over 4400 hours, I know that's not a hole heck of a lot, but for what they go through its a feat.
It could fit under the 3rd gen hood no problem.

 

How would you mount one under the hood and safely discharge the exhaust?

 

just trying to get an answer and now I get a bunch of useless information about airplan motors and theories about how to fit them in a car.

A post about rotating tires would serve more purpose than discusing the above.

 

please, moderators, somebody, put this thread to death

 

I agree. I'll start another thread to try and get answers there.

 

Free Bird:
__________________________________________________

"just trying to get an answer and now I get a bunch of useless information about airplan motors and theories about how to fit them in a car."
__________________________________________________

Are you even listening? You had several people give you some really good information, especially 83 CrossFire TA.

Relax, Free Bird - a little deviation was caused by someone bringing up using jet fuel, it didn't take any attention away from your problem...

No harm done

 

he got his answer. he just doesnt like it.

my solution is even simpler.
bring a timing light to the track, and dont spray a 300 shot on the street.






anyhoo, back on the airplane subject, just because its technical and more intresting the the usual mindless babble that you could reply to by simply quoting 1000 other threads on the subject.

besides the dry stump converstion, what else do they do to thoes LSx motors before putting them in airplanes?

 

I don't spray at the track, hell I don't even run at the track. Why would I want to change my timing everytime I wanted to hit the button? I didn't spend hours of my time hidding the nozzles, noids, lines, controller, switches, fuel cell, pump, filter, bottle, and everything else to tell people "excuse me while I retard my timing before I line up w/ you."

Evidently there isn't a better way.

 

a digital aftermarket timing computer is also a option. pricy, but a option.


im not talking about a retard box, but one of the digital ignitions.

 

300hp on the street… yea, right… you’re less then an hour south of me, I want to see you use that without either: killing yourself or others and still run faster then you would with a smaller shot. For that matter, there is nothing that you can do that is even vaguely legal on the street with any significant shot of spray.

I’m not going to go digging through this whole thread to figure out what you’re doing that makes it impossible for you to pull more then 9.9 degrees, but you can decrease your total timing (chip or mechanical, whatever you have), and every manufacturer that makes ignition box goodies has a retard box, or a modal to work with an aftermarket ignition box that will retard at least 15, 20 or more degrees (in some cases you need to do it in 2 stages to get into the 20* range). Most of the programmable ignitions will let you adjust much more then that.

Lastly, like I already said, 300hp worth of spray is well into he range where you can’t just go “well, I need this and this jet and retard X* for every 50hp” it’s where you actually have to tune it to get it to work properly.

 

Crossfire, check your pm's. If you want to see nova or a secondgen camaro put down a 400 shot on the street give me a call. I've seen it done. Just b/c everyone complains about the track not being prepped and they can't hook doesn't mean everyone has the same problems. People are so quick judge what they haven't seen. I didn't expect you, of all people, to call BS but it looks like you are. So I'll show you other cars, since mine is obviously not done yet, that can do it.

If you would like to discuse it farther, an see some d a mn good street racing, please call me.

Last but not least, thank you for your help and your patients.

 

I’m not calling BS on anything, I know that you can hook hard on the street, or with radials... and mind you this is coming from an old street racer (not exactly old but I’ve been doing it for years), but I think that a 300, 400… shot on the street is not a good idea, and like I’ve already said, plugging 300hp into some formula that tells you that you need X jets and Y timing retard is a quick way to a bucket full of loose engine parts.