IMPATIENT 1

i've been thinking bout jus locking the timing on my lil dragboat motor jus to take away 1 variable in the tune-up so i can concentrate on fuel system tuning right off the bat. i did this when i tuned a twin s475 blowthru c&s 496bbc and it sure made initial tune so easy.

what will i be leaving on the table if i locked the msd6012 timing at say 14* all the time, i'll be injecting meth with a ais 3nozzle kit, my jetpump should flash to well over 5000rpms with the flatfoot of the throttle leaving the hole. my turbo is a small turbine/shaft 1.1 ar s480 that shouldnt have any issue spooling.rather jus lock the timing at a safe level for starters, then after ive gotta nice afr tune on the set-up, go back and play with timing some.

gna be doggy if i lock it or will it still be pretty crisp nuff to work fine spooling and tuning?

98Z28CobraKiller

iTrader: (17)

Not sure how that MSD works but if it's under 100 KPA and a low compression motor or on race gas, I'd run 24* degrees. Above 100 KPA at 14*. If it's vs RPM, I'd put the breakpoint over 3000 RPM.

XtremeDime

iTrader: (16)

I dont know about other people but my timing table starts at 35-40* advanced @.08g/cyl and slowly goes down to about 17 once Im in boost. I would think leaving it at 14* all the time would make it run like a dog and hurt spool. Im not an expert though.

hellbents10

iTrader: (10)

In a jetboat that would be OK for starters, just a little slower into boost is all.

IMPATIENT 1

thanx for the advise fellas


anybody have a timing chart for a good runnin boosted ls motor? i built myself 1 last nite with the msd software but im not totally sure im doin the map sensor retarding right

give me sum ideas on how to time this thing guys, jus need a safe program to install that i wont have to worry bout until the fuel system is tuned in. didnt take me long to get the c&s 900cfm carb on the tt496bbc making perfect afr's, and then i was able to play with timing to the btm system and make it spool faster without affecting afr any

overhere

iTrader: (2)

this is how i have my timing on my turbo lq9. has 36* at 1100rpms thru redline. then pulls timing out to 18* at 6psi and up.

IMPATIENT 1

Overhere what fuel are u runnin? I torched a new 2 piston pretty bad but was able jus to throw in another piston but my afr was ok at the time.i am runnin 30* locked till boost comes in then i ramp it down to 15* by 5lbs.. have the rpm table locked at 15* and the 2bar map table doin the advance work..
my question is with 93 and 2 #5 nozzles spraying 60% meth 40% water is 15* at 17-19lbs jus too much? Afr wasnt lean and somehow i torched a cyl 2 piston so im lookin for the cause before i hurt it again.i jetted up the secondaries to richen it up more and have been leaving on the #14 preturbo nozzle so its gtn total of 24 from the nozzles above 8lbs. im gna shoot for 10.8-11 afr on anything above 10lbs just to keep pistons alive.jus wanna make sure im not hurting it with too much timing.i need to make 18lbs to runnin the boat the way ive got it setup.im proud to say itll run 105mph with a smallbock hehe luv it! Lil tunnel hull hauls *** at 18lbs! Busts 100 within 700ft from a stop

overhere

iTrader: (2)

holy old thread. I think at this time I was running a procharger but don't remember . and was on 93 plus water/meth. but I did melt a piston down on this engine. I really don't know about the timing. im trying to get my tune up correct right now on my new build.

sounds like a bad *** boat for sure!

IMPATIENT 1

Goin into boost hasnt been a problem im actually having the opposite issue.if i try to leave flatfooted it blows my jetpump dry and cavitates till it reloads nuff to hookup hard again..so im leaving on primaries and bring in secondaries as boat takes its set.pretty wicked boat leaving, i can be set and into full boost(17-19) in less than 20ft from start. the boat turned out jus what i wanted to build.be lighter than the guy lining up next to me with a much better power to weight ratio..with this cam and s480 at 18-19lbs its making 850 im pretty sure if not more at the crank and total boat weight with me in it is alil less than 1250

3pedals

iTrader: (3)

93 + water meth at 17* timing works for me on the street with 10psi, but I think at 16psi+, you should put better fuel in it, taking timing out but still running "****" fuel is still on the edge of deto in my opinion. Look into 100ll av fuel, lots of nay Sayers , but from my experience it is GREAT FUEL

knuts82

I second the 100LL.. Its cheap easy to get and Ive ran it in my turbo snowmobiles for years with great success..

lsxmalibu

iTrader: (50)

I lock mine out @ 17 degrees as soon as the engine sees boost. Works and runs great

IMPATIENT 1

I would but it kills our o2 sensors within 10-15hrs of run time.too much lead in it for aem sensors we are told.the watermeth is already taking mine down, i have to set and let the o2 calibrate before firing off.didnt do that till i added the preturbo injection.guessing the added watermeth is jacking o2 up.ive backed the injection nozzle preturb down from 14gph to 3gph today cuz 24gph total from the a.i.s 3nozzle makes it run shitty till high boost.i checked devils own nozzle size calculator and its tell me 17gph worth of nozzles is what i need.not sure how rodney came up with me needing 24gph from the 3 nozzle kit.im at 13gph now and gna try that and keep boost around 16-17lbs on 93. See if pistons can live at that on pumpgas.ill report back later this week on how its runnin afr etc.. all it takes to beat 90% of the raceboats around me is to do 95-100 within 800ft and it shld still do that with alil less boost.if i fall alil short i can tune my tunnelhull to be alil looser to compensate and the mph will pickup some.i run the boat pretty flat now so alil more jetpump nozzle will gain me alil more mph.jus gets spooky on the big end doin a 100 in a 16ft tunnel.the higher i fly the boat the more likely it may hook a wave and force a sharp rh or lh turn and pitch me outta the boat.my 16yr old daughter races the boat too so i prefer to setup to be safer and not pitch prone lol loose is fast tho no doubt

3pedals

iTrader: (3)

I hear you about the leaded fuel killing O2 sensors, that is the way it is. It may be a nescessary evil you want to deal with as opposed to fixing an engine that goes into Deto.
Others have pushed pump gas further, but I believe your boat is going to load the engine harder than any car could be

knuts82

I have found if you mount the sensors on the topside of the pipe and near a 90deg. turn if possible so that they dont get buildup in them they will last 20 times longer. Hell Id bet I have 500hrs on one that is a few years old and still working. And Im running AEM.. On straight 100ll

IMPATIENT 1

Thats where i have mine in the dump pipe.at the bend but up it but up on the pipe nuff that the sensor points down slightly.my hotside was coated internally as well and sweats alot.it can sit for a week and when i fire it off bout a 1/4cup of water exits the turbine. in a spray, sure builds up condensation.

yeah we killed my uncles aem sensor with avgas.didnt last 6-7hrs total runtime.we copied my turbo setup for his tunnel but he used the 10 to 1 alum 5.3 with a s475.he torched a piston(#7) and we recently installed a dual nozzle devils own kit on his. we run 29* locked outta boost 14* by 3lbs on his.he no longer detonates but we are still tuning nozzle size on it.we put a 7gph in hat entrance and 10gph on compressor outlet.same aem wideband i run too.he has twice the hrs on it compared to last sensor and his still calibrates quik.mine doesnt

IMPATIENT 1

It could be loading harder.the jetpump is basically like a dyno load cell.we have impellor chart that show what each impellor size absorbs in hp compared to rpm.my impellor shows to need 900hp to turn 6700rpms..i hit that so quik the boat has to play catch up.the jetpump dont care what size or weight the boat is, its still gna take x amount of hp to turn x amount of rpms.same motor and pump should pull the same rpm in another boat weighing 1000lbs more or 1000lbs less.so yeah im with ya on it loading harder than a car.wish i had a impellor chart to post bet u guys cld help me tailor the timing to the absorption rate of impellor.ill go to my fav boat forum and grab a chart to post.