83 Crossfire TA

iTrader: (2)

This is kind of interesting, we've got one experienced person that has had a fast running combination that the rest of us feel that shouldn't have worked. I know that I would have never even tried platinum plugs in that combination and if I was tuning it, started adding timing and saw that it was getting faster I would have chickened out and not added any more timing well before that point thinking "it seems to be working, it seems to want it but at some point it will hurt it"

The really interesting part is that it's not like you're a little out of the ordinary, most people wouldn't be anywhere near that timing, and if they were they'd be pulling it at the top end and going faster because of it.

I'd love to know for sure what was going on. I suspect that your A/F was actually way rich but you weren't seeing it because of the spray and the platinum plugs, but that's just a shot in the dark.

Shagwell

I run almost 30* with over 600hp worth of spray, but my set-up is very different than a "street" combo.

whatever84

Hope you get it going again soon. Post the times when you do...Subscribed

Mark.

87_TA

The car was rich as stated, It had been running near 12.0/11.9ish.. Not sure I undertstand the comment about pulling timing and going faster as a result.. I have been tuning and running this combo for many many years now
and am very confident with my set up and tuning.. I certainly know where the failure was at this point and it was a result of me getting a little crazy with the fueling as a result of adding HP being added and not reducing timing when more spray was accidentally found through the solenoid having swollen seals.. I am also confident ity would still be living had I not leaned to 12.8 range.. Though it picked up 50hp on the dyno, it was playing with fire - and I got burned..

I still do question the lean spikes from the toggling of solenoids when controlling flow, I do trust what Shagwell and diggler are saying - But It is rock steady after full flow is achieved and has my attention - On the dyno it was spiking to Since I removed the buffer of my global richness I may have had issues starting there - no doubt still aggressive with timing and fueling..

Looking forward to getting it running again..

87_TA

Here is the Dyno showing spike of 16.5 AFR - When pulling N/A no spike at all..

Orr89RocZ

iTrader: (20)

Another note on dynos. They do not load the car as hard as real live pulls at the strip or on street. Saw it on my 383 slightly but really noticed it on turbo car where it made 2 psi less than it did on the street and ran half point richer! If I tuned to peak dyno power and leaner afr and went to track, car may have blown up. So try leaving dyno abit rich and track will lean it out more

87_TA

Good Note! Thanks, I will keep that in mind - That may have helped a little here as well..

On a side note - Putting Vega back together, started putting block together this morning.. And on another note, taking my diesel to track thursday if weather is ok..

Orr89RocZ

iTrader: (20)

Been trying to get the TA out to the track but I usually have softball games thursday night I wanna get a pass in or 2 before the drag radials are completely gone...but I'll be getting more soon.

87_TA

You can borrow my 28" hoosiers if you like.. Also have a set of 28" et streets here.

Shagwell

Definitely want to stay a tad richer on the dyno than "optimal". A 2-3 second burst pulling through one gear is not nearly the load placed on the engine through a full pass. Only chassis dyno pulls I've made were on motor to establish a clean carb tune-up. I tune the spray at the track according to the plugs & the time slips.

You had a combination of things that caught up to ya on this deal. - Leaning it out showed power, but obviously it having been that rich was covering up an over-timed condition. I would bet there's still power to be had keeping it leaner/cleaner but backing the timing off to where it's happy on that tune. In fact, I would bet you will see a broader curve & even possibly more peak yet.

Orr89RocZ

iTrader: (20)

I got my old ET streets to try if the drag radials dont hold. The ET's are old and getting abit hard. Last time out they spun abit on the turbo car but should hold the TA since it has half the hp

87_TA

Update:
Short block back together, bearings looked great, just honed cylinders, replaced 2 pistons due to ring lands crushed some, replaced all rings..

May have found a contributing factor, when heads were ported they cut intake runner into the push rod holes an epoxied - the 2 cylinders with the heavy detonaton the epoxy was pulling vacuum from crankcase.. Not only cause but oil mist can certainly aid in detonation.

Alsl have my BBC short block together - not sure which car I will finish first as they are neck and neck right now. And will have been a while since both were running well..
The BBC got new rings, bearings, sleeved # 6 cylinder and awaiting new valve springs.

Orr89RocZ

iTrader: (20)

Interesting. Wonder what kind of epoxy was used? Top stuff i seen recommended is a-788 splashzone. Could weld it up and if pushrod clearance is off, could run an offset rocker

automec

my dart pro 1 headed small block likes 40* but i am up at 5000 foot eleavation. i have run this combo for 8 years . never hurt a piston or a plug. 4 years ago , last time it was apart, dynoed it and it made best power at 40*. i hit it with 150 shot pulling 6*. it made 852 @6600 on the dts engine dyno.

i say give the motor what it wants.

1gary

Didn't read the whole thread.My bad.Are you running a separate tank for the nitrous shot of 114 octane gas??.

87_TA

Just an update on the project: Back running as of today! Watch out
Have boffa cars running, been forever since that has happened.. And best of all I see no leaks in either! wow.

mw66nova

iTrader: (13)

nice tom!

Shagwell

Sweet!

Orr89RocZ

iTrader: (20)

Glad to hear that!

whatever84

That vega looks nasty!!!


Mark.

87_TA

Thank You!

87_TA

An update on this - Car been back together for a while but Vega was taking priority.. Just finally took to track thursday in a rush afetr work.. Only really made one pass with a very rich 150 shot and Ultra conservative timing 29 degrees and conservative launch at 4k bogging to a 1.62 60ft - went 10.1 @ 139.. Second pass upped rpm to 4900 spinning to a 1.61 then running out of spray.. Forgot to bring other bottle, was not sure what remained in the one in car. Opps...

Will be back to track soon, just got fresh inspection and Exemption today.. Will start turning up the heat slowly getting back to where it was..

Orr89RocZ

iTrader: (20)

Lol i just passed inspection today myself

87_TA

Getting it sorted out, had 3 bad passes tonight getting it sorted out, but ended with a 9.8 @ 141 on a 1.48 60ft.. Very rich 175 tune on only 29 degrees timing..
Something strange on first pass, my N2O solenoid which is new from last year stuck in the off position on first pass - had to hit it with screwdriver while energized to get it working.. Not sure why that happened..

Getting her back into shape

91_B4C_RS

What does it run on motor alone?

Shagwell

Bottle pressure & check grounds.

I'd still pull the timing back a little more, clean up the fuel, then play with the timing. Being a few degrees softer than needed won't hurt anything except power, being even 1* more than what it wants can easily eat stuff.

87_TA

Both noids ground to together then back to controller, Bottle pressure 1000.. I powed the solenoid, then hit with screwdriver that broke it free.. No issues rest of night.
Yeah, working at it slow and conservative to get it back where it was - Plugs certainly rich, I still believe now it was the breech in the intake ports sucking oil that caused the detonation - especially being those 2 were the ones that failed - But still playing it safe, I will lean a little and pull some timing to 28degrees while fueling, thanks..


10.41 best, high 10.2s capable at a sticky track is obtainable at good altitude..

Shagwell

For note, but both Monte from NOS & Steve from IS recommend no more than 950psi bottle pressure; usually 900. - The % of pressure change during a run is considerably less there than at 1k, but is still plenty high for it to hit clean & smooth through the entire run.

87_TA

Last Update on this project: Took Back to Dyno as I am planning to push it harder now reaching end of year. As there was so much debate over my choices of timing I was happy to see that the car still wants the timing.

Started N/A at 34° - with A/F near 12.3-12.7. was able to flatten more to 12.7-13.0 which I gained a few HP, Raised to 36° and gained 10hp, raised t 38° and raised 5hp, Raised again to 40° and gained 1 hp.. So I backed off to 38°

On the spray - A/F was about same as First N/A pass at timing at 26°, leaned out A/F slightly with a loss, increased to lower 12s on and gained 5hp.. Increased timing to 28° and gained 8hp and plugs showed no sign of detonation. Increased to 30° and gained 4hp - So I backed it down again to 28° and tried some additional fuel being it liked the first richen up, and it lost 5HP..

On a down note I seemed to have lost power across the board by around 20.. Could be DYNO/AIR/Whatever..

DIGGLER

iTrader: (1)

does your dyno sheet std or sae? and was the last dyno std or sae?

its good to see your getting the nitrous sqared away, hope to see some pass vids soon!

87_TA

They are both STD... I have to get hold of the new files, but looking over the curve I had cut a lot of fuel at peak (4900rpm) that may have been the peak problem.. 13.2 VS 12.5 - However, look at the rest of run I think power is about the same.. I will have to see..

But the car was 30 down on motor only pass - Which could have been the use of race gas (112) The car does lose on race gas, but did not think I would lose that much. Peak was also down 300 RPM which was strange on motor only. But looking at last passes I was much more aggressive on fueling being 13.4afr at peak power vs 12.7 now.

DIGGLER

iTrader: (1)

peak being 300rpm lower is very interesting indeed..... when it peaked, was it a nice, easy arch, or was it abrupt like it was falling off a cliff?

87_TA

Its smooth, waiting for the graphs to study against the old ones.. I think it may be AFR related still - Being My HP is pretty flat from 55-63 being with in 5 hp of peak on the old graphs.. Other thought is where the intake ports are epoxied we had to build inside the port slightly on 3 cylinders for strength, though minimal it may be hurting flow.. Really hope that is not the case - Kinda thinking his wideband is not very accurate, being mine is showing half point richer than his.. Ill post up the new vs old when I get it.

DIGGLER

iTrader: (1)

could be like you said, wideband acting up. 300rpms on the curve just seems like alot to change just by adjusting a/f. might be something you can change at the track watching your mph between adjustments....

87_TA

I imagine that is what I will do, not a guy to put lots of stock in a dyno anyway.. But hate seeing a lower number..lol, but if it runs the number really don't care..

87_TA

Just a thought - I have switched to ultra cold AR3932 spark plugs for spray, you think this could be the issue? I image that is part of the issue..

DIGGLER

iTrader: (1)

might affect things somewhat......
how cold is that plug compared to a brf7 ngk? if its waaay colder, i would say its too much. i figure a brf7 or 8 should work for your car.
in my mind, as you add timing and the car keeps picking up, and the heat mark goes past the bend, you need to go to a colder plug. i would think running an ultra cold plug you might not ever get a heat mark on the strap at all. some guys at that point would continue adding timing trying to get a mark on the strap, and wind up killing some pistons. (if they would watch their timeslips they would see they were going in the wrong direction)

87_TA

Well a -7 NGK plug is comparable to AR3935 Which would be near optimal for my car N/A.. The 3932 is comparable to NGK-10 which is aggressivly cold, but I did go on the agressive side for the spray.. Little to aggressive I suppose - The heat mark is near end, which I did not try to move with timing.. I should probably go 3933's for the spray.. I imagine that affected the power some N/A and with race gas on top of that..


Here is a decent site with plug reading info and cross referance table.. http://www.wallaceracing.com/plug-reading-lm.html

Orr89RocZ

iTrader: (20)

That probably was some of the power loss. Seen guys post gains with correct for the engine spark plug swaps. Too cold will likely be down some. 30 hp? I dont know... But some is def for sure. I run a ngk 8 range plug in the turbo car. It also seems to like more timing than i would have guessed but oh well. Different heads different chambers different timing

87_TA

I Imagine the race gas cost me 10HP on motor as well, The nitrous passes were only down 12HP after review, so may be on to something..

mw66nova

iTrader: (13)

excellent article on plug reading tom, thanks for the link! i've been looking for a good break-down like that for a while now!

DIGGLER

iTrader: (1)

how much compression? i know you've posted it before but i cant remember
i would still say around a brf8 or so? you see 10's in the 400+hp shot tunes......

Orr89RocZ

iTrader: (20)

The type of gas Could also cause power drop. Just reminded me of an engine builder on another forum who tested every kind of 93 oct pump gas he could find and said chevron 93 was the best i believe. There was 10-15 hp difference in just the brands of 93 oct, let alone what could be found in race gas mixes when car doesnt really need the octane

87_TA

Compression is 11:1 - Are the brf8s 3/4 washer plug? That is only 1 colder, I plan to try a 325HP on it, so you think I should go with the 9s or AR3933s?

You are welcome Matt, I thought it was a good read as well..

Yeah ORR, I really should have tuned on Pump, then added for the shot.. Beside I am not even sure of the specific gravity of the C112 compared to pump either.. If anything though pump should be a little leaner I think which will be better anyway.

DIGGLER

iTrader: (1)

the brf8's will be a tapered plug. if you need a washer, check into something the same heat range as the brf. (not sure what it would be)
once you get up into the 300's you might need to go colder.... like those 9's.
for now i would try playing with the 7's or 8's to see what the heat mark does.
should fly with 300+!!!

mw66nova

iTrader: (13)

gonna really test that spec 3 with 300+!

87_TA

LOL, not promising anything yet.. The car really needs a gear change to take advantage of spray.. Especially being my power range on spray is from 5-6 really, and I go through traps at 7300 now. 300 will only enhance that problem.. But we will see what happens when I get to track, I am also sure these new slicks are already shot - being last year I drove them home from Maryland when trailer broke the wheel - that was first day on those tires too!

I will get new plugs right now..

Orr89RocZ

iTrader: (20)

You got 6 speeds. Plenty of options for
More speed haha. Just shift again lol

87_TA

Lol, this thing barley goes into 5th normal driving, I could never power shift it to 5th..

Orr89RocZ

iTrader: (20)

Bummer. I remember you hitting 5th at mir that one weekend