FABO racers, could use your help to win a bet.

-
U

UOP

Well-Known Member
Joined
Oct 29, 2009
Messages
759
Reaction score
55
Location
Plano, Texas
Well, I went and let my ego get me into trouble again. Yup, good ole peer pressure at it's finest. So here's the skinny on the bet. Myself and a few other guys have all gone in on a fairly substantial pot to whoever can reach their goal first, in 1/4 mile et. A couple are shooting for 11's, another is trying for 12's, and I've got to run a 10 sec pass to claim the pot. I think I have a good shot at winning, but need some help from the more experienced racers here.

My combo:

1986 Mazda RX7
2900 lbs, 3150 with me
No weight reduction other than fiberglass hood

360 magnum
Stock bottom end
Stock heads, untouched
216/224, .506"/.506", 114 cam
MP .525" lift springs and MP non beehive retainers
Mopar M1 single plane
650 dp
1 5/8" block huggers
2.5" dual exhaust, x-pipe, straight thru mufflers
Locked distributor with MSD Programmable Digital 6
20 initial / 34 total timing on 87 octane
Walbro 255 lph fuel pump

Extreme Automatics built 200-4R
Gear ratios: 2.74, 1.57, 1.00, .69
Revmax 9.5" 3600 stall

Ford IRS 8.8
New Trac-Lok with carbon clutches
3.73 gear
275/50-15 (26") Drag Radials

-------------------------------------------------------------------------

Typical 1/8 mile run in decent air (1568 DA)
Trans shifting itself at 5000 rpm

60ft - 1.63
330 ft - 4.949
660ft - 7.71
MPH - 87.66

I know that's short shifting but I do it for consistency and rarely manual shift unless it spins. If I were to manualy shift at 5700 (where I stop seeing gains) it would run something like 7.65-7.68 @ ~88 mph.

Unfortunately I don't have a 1/4 mile slip that matches the conditions of the run above, but if the car will run good 6.90's in the 1/8 it should go 10.9xx in the 1/4. Well, that's what I'm thinking anyway.

------------------------------------------------------------------------------------------



I see that this is starting to become a long post so I'll sum things up a bit. Do you think a 100 shot will do the trick? Currently I don't want to do any major mods (cam swap, gear change, etc) due to the fact that I run a 7.65/12.00 cut-off class in a bracket series and am already at the limit. Plus, I'm going to be the defending champ next year so I don't want to change my n/a combo that much.

If the 100 shot would do it, I have another small delima that needs addressing. I think I'm going to run out of gear. Currently I cross the 1/4 mile stripe at 5700-5800 at ~113 mph. To run a 10.9xx I'll at least need to run 120, probably 125. That would put my rpms well over 6k, which is way out of my useable power band. Would that hurt anything, meaning engine damage?
 
10.99 is about a 6.98 in the 1/8, so you need about 3/4 second reduction. a 100 to 150 shot should do it for you. I will suggest using a nos cheater system, it tunes from about 100 to around 250hp.
 
IMO, you will need a little bigger nitrous hit to get in the 10's. If you are going to spray your way to the 10's, you will probably need a 150 hp hit to solidify your goal. Your current 1/8 mile times reflect a low 12 second 1/4, probably in the 12.1-12.0 range.

Yes, if you can get a 6.99 1/8 mile, you should have the back end to reach the 10.9x range. So, currently you will need to drop your 1/8 mile time by 0.7 seconds and increase your MPH in the 1/8 by ~ 10 ish (97+ MPH would probably do it, or 120 mph in the 1/4 ). FWIW, if you were to trap 125 mph in the 1/4, then you would have a mid 10 second capability with a good chassis setup.

Good luck.
 
I would venture to say the NOS will get you a clean run even with that gear and higher RPM range as long as your valve train don't start to float. If the valves float you if course could have damage as you know. I would check your valve springs just to be sure. The rest of the engine should be able to take it no problem. I would also probably take out your revv limiter. Most guys that Run NOS don't use them. An NOS backfire up in RPM when it comes off the limiter is not good either.
 
Mad Dart said:
I would venture to say the NOS will get you a clean run even with that gear and higher RPM range as long as your valve train don't start to float. If the valves float you if course could have damage as you know. I would check your valve springs just to be sure. The rest of the engine should be able to take it no problem. I would also probably take out your revv limiter. Most guys that Run NOS don't use them. An NOS backfire up in RPM when it comes off the limiter is not good either.
Click to expand...

For what its worth, my rev limiter was probably the only thing that saved my old motor from grenading when I broke the yoke on the rear end during a nitrous launch years ago....it pegged the 7000 rpm chip in a heart beat...I could not have reacted fast enough to save it, but the chip did.
 
I too believe a 100-150 shot will get you into the 10's.

IIRC, you have a converter that is on the tight side which will pay a benefit when you smack it. The mph on your best 1/4 run is light for the et, which the nitrous should help square up.

I'd start with a cheater kit, jet it ~47/40 for 100 shot, 5.5 psi flowing, pull 6* timing and run it. See what you get. Then start tuning the juice. If you need jet singles, one of the least expensive places is Nitrous Supply run by Mike Thermos. He started the company NOS way back. About $4/jet.
 
The valvetrain floating is actually one of my main concerns. I've had the rockers off fairly recently and didn't see any obvious signs of float but I honestly don't know for sure. My advertised cam lift is .506" on Comp's XE lobe so does that make a difference?


As for running nitrous, from what I understand my motor should love it. I will admit the combo isn't solid (small carb, small cam, and a single plane) but in my defense it was intended to be boosted and I have been told that should be good for nitrous too. The car has run 11's before but that was before swapping from an Edelbrock Air-Gap to the MP single plane.


When it comes to the rev limit, I can set it anywhere it needs to be. Also, I plan on using a window switch to control nitrous activation so it won't be on under/over a certain rpm range.
 
flyfish said:
For what its worth, my rev limiter was probably the only thing that saved my old motor from grenading when I broke the yoke on the rear end during a nitrous launch years ago....it pegged the 7000 rpm chip in a heart beat...I could not have reacted fast enough to save it, but the chip did.
Click to expand...

Everyone I know who is serious in the NOS Game does not use a limiter or it is set way out past the redline. All I was getting at is bouncing off the Rev Chip on NOS is not a good thing especially with stock parts "Rockers etc"
Carry on…...
 
Well that's 2 votes for the NOS cheater kit. The 4 kits on my list are NOS Cheater, NOS Super Powershot, NX Hitman Plus and NX Hitman. The NOS Super Powershot and NX hitman seem to be direct competitors, and NOS Cheater and NX Hitman Plus use the same plates but come with bigger solenoids. I guess the question is do I need the bigger solenoids when I only plan to run at most a 150 hit?
 
I just installed an NOS Cheater on my Scamp that has the 9:1 - 410ci motor in it. I did a stand alone Fuel Pump with a lil Fuel cell squirting VP110 on the hit. Motor is fed with 91 Pump Premium. I got a safe tune in it, only a 150 Shot and I am taking out 7* on the hit. It hauls the mail is all I can say. I got some pics in the last pages of the scamp thread in my signature.

The NOS Cheater Solenoid's say they are good to 250 hit. My friends have used these same Solenoids for over 300hp hits so I believe they are under rated.
 
Based on your current 1/4 et I'd say a 150 shot could go mid 10. Also basing this on similar combos I have worked with. I don't recommend what I haven't done. Good luck and go get your money!!
 
Good info,every where. Subscribed. FWIW,Cracked back,usually dead on ,N20 tuning. The windows switch,should be interesting.
 
Abodybomber said:
Good info,every where. Subscribed. FWIW,Cracked back,usually dead on ,N20 tuning. The windows switch,should be interesting.
Click to expand...
Window switches are for the scared!! :D
WOT switch is where it's at, I don't even like the push button setups some have unless it's just to purge through the motor :glasses7:
 
120-122 will get you into the 10's with a decent 60'. Shoot for a low 6.90 and 98-99 mph and you're in the money! IIRC, a 6.94 and 98mph is about equivalent to an 11.00-120

As long as the valvetrain is stable, that engine should turn 6500 without much issue. I've turned a hyd roller engine with stock mopar lifters 7k+ with a cam just slightly larger than yours.
 
Abodybomber said:
Good info,every where. Subscribed. FWIW,Cracked back,usually dead on ,N20 tuning. The windows switch,should be interesting.
Click to expand...

Yeah he's really helped me out in the past, especially when I was getting the car ready for Drag Week last year.

SpareParts said:
Window switches are for the scared!! :D
WOT switch is where it's at, I don't even like the push button setups some have unless it's just to purge through the motor :glasses7:
Click to expand...

Well, I am a bit nervous about it. I have no dea how hard a 100-150 shot will hit out of the hole and I don't run slicks. Granted my car seems to work well with radials but I'm upgrading to the M/T ET street radials for some extra grip. I will be using a wot switch for sure though. I've also been looking at timers to see if that can get the job done.

crackedback said:
120-122 will get you into the 10's with a decent 60'. Shoot for a low 6.90 and 98-99 mph and you're in the money! IIRC, a 6.94 and 98mph is about equivalent to an 11.00-120

As long as the valvetrain is stable, that engine should turn 6500 without much issue. I've turned a hyd roller engine with stock mopar lifters 7k+ with a cam just slightly larger than yours.
Click to expand...

At this point I'm thinking my 60' should be better than 1.55 and I was also thinking 6.90 would be a good number to shoot for. Whether or not 100 shot will do I don't know. As for the revving, a Dakota guy I race with is telling me the same thing about it being no issue to rev as high as I'm looking as long as the valvetrain in stable. Problem is that I've never revved it that high and I wonder if my MP .525" springs are up to the task. They probably are but I overthink everything. Plus I didn't know if revving an engine way past its powerband would hurt it somehow.








Still researching parts, will keep yoy guys up to date on what's going on. Lots to do including a rollbar and other safety stuff, not to mention fixing the rear subframe I broke my last time out.
 
IMO, your 60' is really good for the ET. 1.55 is usually good for a really low 11, 11.10-11.20 timeslip. That's an issue most people would love to have!

Shift where it runs best and run it out the back.
 
Always used the throttle switch,myself. 1.55 60 ft.Indeed!!!
 
Ok, been doing my research and am pretty sure I've got a game plan. Makes me sort of glad we all agreed that a winning pass can't be made until next year because I have a lot to do. At least I should be able to TNT enough to dial it in.

The car is currently torn down and is getting ready for a roll bar/seat/harness install, along with everything else needed to be legal to 10.00.

I think I found a great deal on a nitrous kit and wanted to run it by you guys before pulling the trigger. There is a local guy who is parting out his build and has a NIB Super Powershot kit and is willing to let it go cheap. On Summit's site this kit is only $10 cheaper than the Cheater kit ($569 vs $578 ), but he's willing to let me have it for $425. Does that sound like a good enough deal to you or would you still go for the Cheater kit?
 
Yes that kit will work fine.

New they are 440ish from amazon with free shipping. If the bottle is full on that guys kit and he has all the jets, not too bad of a deal.
 
Do you already have a bar in the car? From the times I'd say no - but if you run that fast you'll only be allowed to do it once before they toss you. So add in another 100lbs for the bar and plates. Already seems kind of heavy for a Mazda with a small block but maybe they're heftier than I thought.
I think you'll need the Cheater myself - and I'm not sure the ring lands will hold up. But it's not a big $$ engine so I'd say give it a whirl.
 
I ran the NX Hitman setup on some of my cars.. Worked great. Go ahead and buy a kit that you will plan on using for a long time.. Once you spray it and make a clean pass you will be an addict.. Shoot I got all the way up to 4 kits on my old car on a progressive controller..

Read your plugs and do it the right way.. Run the car all the way through on spray. Shut it off at the finish line and let it coast to the return lanes.. Pull the plugs and see how they look. Do not wait until you get back to the pits unless you tow it back. The jet settings that come with the kit will be very fat...Buy some extra jets so you can correct this.. Nothing like putting in jets thinking you got a 150 shot and after it being so fat you netted 90.
 
Car is getting a rollbar right now along with several other safety items to be legal. I'm going to see if I can offset the weight by removing it elsewhere so hopefully it'll be the same or lighter when all done. My particular car is considered a luxury model with power everything, extra sound deadening, etc so that's why it seems a bit portly.

As for tuning the nitrous I will go about it pretty slow. I wound up not buying the kit I mentioned the other day, it sold before I got there. So much for holding it for me. Oh well I'll pick something up soon.
 
You must log in or register to reply here.
-

Back
Top