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A while back on a thread you mentioned the need to change jetting when running BP100, but you didn’t say whether it needed to be increased or decreased.
So which way do you reckon it needs to go? Go up or down in jetting?
Simple explanation on jetting with different fuels. Rough rule of thumb: Less dense/lower specific gravity fuel = upsize jets. Avgas/BP100 SG = ~0.70, BP Ultimate = 0.75, Toluene = 0.86, Nitro = 0.88........don't blow yourself up!
You'll have to take some of your home brew nitro to the lab and check it's specific gravity! Theoretically, if it's the same as BP100 you should be real close to the correct jet size? +/- a bit??
According to that 1st article that could be up to 5 jet size increase, much more than I anticipated. I see also with your posted sg's that the toluene has been offsetting things a bit.
Reason I'm on this track is I ran the car up on straight BP100 and you can tell the motor just loves it, it's stop stalling at idle and has a whole different note to the exhaust, maybe a tad quicker - hard to tell - more torque but maybe less top end.
By the way, what area of Perth do you hail from? Have to have an eye ball of your car one of these days and swap some notes...
Mate, I hail from up in Mindarie. I used to live over near your neck of the woods years ago.....was that Kalamunda area?? In fact I even used to work for the old Bell/Boral tyres about 12 years ago on Kalamunda Road - great for cheap rubber!! My career path is a little different these days!
Holy cow, I just saw your 12.4! You've shaved 3 tenths off - and on street tyres I assume. Take the sub woofers out and with slicks you'll be in the 11's
My gtech arrived this week!.....I've got issues. I'm too embarrassed to post my times!! But I have some light at the end of my tunnel. I could only get a 14 sec pass out of her. I've only rebuilt the bottom end so far and put my stock OC 2V's back on with standard valve train and warm hydraulic cam. I was in the process of getting some bracket master style 2V closed chambers....but then the 3V came along and has totally got me hooked. I think for the extra cash, it'll be a much better investment.
I have to launch like a pussy, anything more than 1000rpm with 4:11's and she just sits there and lights up - even with my fat 295's. I get to my terminal speed of 100mph (valve bouncing 5 grand with 4:11's) about 3-4 sec before the end of my runs, so thats killing me and I still have my choking single system.
So - back to ebay - getting a rocker stud/guide plate/HD spring/pushrod combo pack with some large fries for $220. I'll put my new crane rockers on and she'll be good for 6000rpm (120mph). Plus the pacemaker 4-1's and 2.5 twin system. Should be good for low 13's then - next few months. A cheap interum fix until the new heads and big ass solid cam.
Recommend anyone in Perth who can machine my heads for screw in studs? I assume it should be a cheap job.
4.11 are a litlle short imo. Dunno what work youve done to the diff, but a change of gears mite be worth lookin at.
I wanna get 3.7s, but i onlt got a EB 6 :)
wanted a 351 XE, but no go.
How much are gtechs now?
Mite see yas on the streets
Jase
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TPC Mod/henchman
previous rides;
1st car EA Fairmont Ghia, extractors, exhaust
2nd EF GLi, 'custom' interior, extractors, exhuast
3rd EA Fairmont 5spd, low'd, extractors, exhuast, head
work, 3.45LSD, EL dash, interior+ El ECU
4th EB2 Fairmont, EL dash and interior, BBM, LSD etc etc
5th EB Fairmont Ghia 5L. All leather, lowered, exhaust etc
Sorry mate didnt notice the thread :( yer shes a little better thanks.
as for the jets yes you go up when running 100 usually around 3 to 6 jet sizes. Always go the 6 and work back.. better to be fat then lean :) let me know how u go
Cheers Maniac for that, I must have been running well on the rich side of things already because the way its driving now and by the plugs can't see it needing 6 jet sizes more, so will start in the middle of that at 3 and see how it goes. Good that you say this because matches with the info TruBlu supplied on the SG's indicating 5 jet sizes bigger needed.
TruBlu yeah the 12.4 came about on a recent colder night and with the recent chang of fuel. Looking forward to a 'real' quarter run in the future for absolute validation. Yeah LOL ... that heavy sub helps with traction, finding the Yoky tyres have stacks more grip than the Eagers, so providing I launch at half throttle the back end stays facing the right direction.
Mindarie other end of Perth from me, up in the hills, but in the process of moving down to Mandurah. Bought a big boat and jacking me off towing it so far! Maybe we'll catch up at some in between car scene in future.
Wrt your times and build-up, my previous clevo combo in same car had a reasonable Sig Erson hydraulic (Hi-Flo 2H), moderate head work, Edelbrock Performer, 750DP, 3.23 gears and only did a 14.2, albeit a hot night and pinging a bit. The 351 combo before that one, same car, had a torquey but small hydraulic cam, 302 closed chamber heads, 750VS on 2.77 gears and did a 14.4. That motor never wanted to go past 5000rpm.
So me summises that a car running 14 quarters is still a bloody quick car and pretty much what you should be getting with what you are running.
Your 4.11's are textbook ideal for the best quarter mile times with a cam in the 6000-6500 range, but as Jase says bit short with your current combo. Me personally taking a different route and going against the grain, staying with 3.23 gears and doing whatever I can to keep up low end torque. I'm ok with passing the marker half way through 3rd gear. Way I see it heaps of fast cars run 2 speeds and I get a great deal with those gears on the street.
Leon at A1 Hi-Performance seems to be The head man lately, did you see the article with him in latest Performance Street Car? Knows his stuff but personally I've only got advice from him and still go through Alan at AJN's with all my stuff. Have come to trust him over the years, though he does farm out more of the machining these days, think he use Performance Mods in Ozy park. If you do call him, tell him Brad Vivian referred you, sure he will look after you really well.
How do you get 295's on the back of an XD? Shortened diff?
Jase,
Got my gtech on ebay motors (US website) for AUS$82 brand new including shipping. It arrived in 7 days. Beats the rediculous price here!
"Home brew nitro" - referring to STROKEXD's fuel mixing tricks (a few posts back).
I presently have a stock 9" with 4.11's. I agree, damn short and annoying for 5K limit motor. Funny you should ask what diff - I have a new strange nodular casing, detroit locker, richmond 4.11's and all the other good bits ready to build up. I also have a Tremec TKO waiting to go in (0.68 OD drops ~30% rpm), so that's why I'm putting up with the low gears.
STROKEXD,
The 295's fit as a result of the steel flared guards the previous owner fitted. Diff is standard. Here's a pic in my gallery.
The wheels SUCK (got some new convo pros waiting to go on). The rear ones presently fitted are 11 INCHES WIDE!! with a 3.5" offset. A 5" offset would fit on an XD, which would move these in 1.5 inches. I reckon they MAY just fit on standard guards. I'll measure it next time they're off. They look real cool from behind! I've had to fit some air shocks so when 3 fat mates jump in the rear, the guards don't rub on the tyres. No tubs or anything too radical.
Mandurah hey!! I guess the motorplex is a good middle ground! Speaking of boats, I'm off to Exmouth next week for 3 weeks - a tiger shark, few spaniards and anything else big will do. Got to try out my new 300lb handline and overhead combo!!
Thanks for the info on getting some head work done and the reference - it's not what but who you know
I put my current combo on Dyno 2000. Awesome program for playing with motors before you actually make the mods. With the new 4-1 exhaust and valve train to hack 6000rpm, there could be up to an extra 80+hp available with the mufflers dropped. Bring it on.
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