1st things... I realize now that I have gone about things backwards...
General Facts:
1994 LT1 stock 6sp zf
Work done:
Bored and stroked to 383 by Barnes & Reese Racing engines (Circle track shop avl, NC)
All parts ballanced
"Cleaned up" orginal LT1 heads, 5 angle valve job, beehive springs
1.6:1 Rockers
Comp cams custom grind & smaller base circle.. seems to be based on xfi 468 cam for LT1 & 1.6:1 383 combo
Duration @ .050 242 / 248
seat to seat 292 / 300
Lift 584 / 579
Lca 113.0 Icl 109
B&R race engine shop did all mach work, weighing & balancing and blueprinting short of final assembly.
Went with flat top pistons for 12.0:1 CR (all bottom end parts new including high flow oil pump but stayed with stock oil pan) Will change oil pan if we decide to do track days...and we get some real power.

Final assembly by successful "old circle track racer and motor assembler" however, very little experience with computer car. {He wanted to put carb and a mercury marine intake on it(another story)}
I stayed with the stock injectors & rail but bolted on 58mm BBK TB.
Stock Opti-spark
No headers yet but cats cleared, x pipe and open exaust back. its like friday night at the track
Car runs with stock computer ... but not impressed.
So
On the way to the dyno tuner next week with cold plugs.
Question:
What should I expect from the tune?(can it improve it that much)
Should I take it to the tuner with octain boost?
No ses light... but why is the serv ASR and ABS light on?
Should I go ahead and look at changing heads and intake?
Any need for injector change?
Whats a little $$$ for the local economy????
OR it it destin for a boat anchor and I just need to let the race shop start over and do it all their way$$$?

 

on that ASR and ABS light thing, I had the same problem whenever I would get out on the interstate, anyway it ended up being low on brake fluid.

 

Thanks for the info...
and
Checked code for mod 9 got a H63 reading?

 

The intake will work fine. The stock heads are killing it. Probably leaving 50-60hp on the table.

 

As to be expected.
Have more cubes , BIG cam ; stock programming it going to struggle to run right.

 

In your opinion what are the absolute best heads for this combo with road race 1st and street use 2nd ... and your thoughts of why? thanks

 

Best IMo are the AFR comp ports. The LT1 head just wont get the job done here. Intake you can heavily port . There is more to be gained from a single plane but a thoroughly worked over GM intake should get you by for awhile.

Ditch those stock injectors and spend some time tuning, youll have a nice running car. If it were me once you get around 12:1 I wouldnt even mess with a HR, go straight to a solid, night and day diff.

 

A couple of things you either need the stock heads ported by some one like Lloyed Elliot or AI or after market heads to optimize your set up and you should get the intake ported at the same time to what ever gasket set you choose. As far as the injectors this is a never ending debate so I recommend asking the shop tuning the car what they would like to see. I have ran the following injectors with my set up (See Sig) FMS 24's (90%DC) LS style 28's (85%DC) FMS 36's (Still on the car 80% max DC) and FMS 42's (Didn't check the DC, only on the car to see if my 36's were causing another problem.

 

With a 383 and that big cam you have, the stock heads are flat killing it.

I agree with the AFR Comp Ports. Best heads going for the money. I have the AFR 210's on my LTX which my build is somewhat similar to yours. Your cam is about the same at .050 as mine but yours is a much milder lobe (since the seat timing is bigger). With it backed up the way it is on 109 I/C and the long 113 LSA, it is going to want to make peak power around 7200RPM according to my Engine Analyzer. I hope your bottom end is good stuff.

YOU NEED a set of headers! Like yesterday.

I don't think the stock injectors and fuel pump are going to feed it even as is with the stock heads. Marginal at best. When you change the heads and port the intake (which I recommend you do ASAP) you'll need 36lb injectors at a minimum.

LTX's will run on 93 octane at 12.1 SCR with little problem because of the reverse cooling and efficient combustion chambers. I calculated your DCR and its probally in the 8.7-8.9 range, which is still safe on pump gas for LTX's.

Yes a tune can make a world of difference. Mine made about 340RWHP on the stock tune first pull and was so lean (about 20:1) after 2000RPM it melted the Jet Hotcoating off the headers. I'd like to add you couldn't even drive my car on the stock tune. Once the tune was all sorted out it made over 100RWHP more and anyone can drive it.

Once you fix a few things and get it tuned you'll have a good running car.
Will

 

AFR heads... thanks... and the headers... any specific ones you like? (will not have headers by tune day but will add to list for future if tune gets us to respectable performance) then its on to roll cage and suspention. By the way the actual compression measured at 11.9:1 so it would seem I am ok with 92-93 octane as you stated but using addatives anyway.
Testimonial = took a (latemodel Frank Kimmel series) rebuild to the track with pump 92 (too cheap to purchase race fuel on practice day) on an aprox 13.5:1 with about 40 degr advance mech ... someone hooked up the vac advance (car has no knock elect.'s safe guards) Lasted 5 laps on a 1/3 mi track. thats what you get for cheating. Lets just say it was a poster for detonation.
Also someone metioned a more well known machine shop for head and intake work. Good Idea but I think I will stay with the two local shops availble as they have a lot of experience, and resumes of NASCAR & outlaw series winners with bullet proof engines... As far as flow work they are only limited by my pocket book. The porblem is they are not interested in computer cars.
As far as the bottom end its good depending on who you are talking too.. The guys at the shop think it is ok, but they start talking about cranks that have knife edge rotating assemblies, exotic metals, drysumps with specific pickups and supplies, pistons that are so light and short skirted that they look like they would turn side-ways in the the bore they call that HP (also they think KB pistons are 2nd class, and can show you the results.. ouch) so I have to take everything with the uderstanding they are in the 7200 rpm range for 2-3.5 hours (6500 - 9500) and are looking for 3-5 horse power gains in their world and I'm looking for a streetable value $$$ ... and again they are not interested in "computer cars" or "grocery getters" since its not their occupation.
The 7200 I most likely will not do it will be more 4500 - 6200 (the cam selection was based on my ego... they wanted me to use the next one down.) So now everyone agrees that I didn't listen...
The guys at the shop want me to sell the computer motor and let them build a "Mild" street engine -- 350 bored and stroked to 406 with 4bbl dyno sheet at 510hp @ 5500 and will last as long as I change the oil... and as always it about the $$$ and I want the computer & FI. So I am trying to get them interested in RR comp motors for want-a-bees track day guys like me, so thanks for helping me get up to speed... and I have lots more questions to come like aftermarket comp & FI systems like FAST?

BB

 

: thumbs:

 

Headers - I have Exotic Muscle (EM) 1 3/4" primary. I'm happy with them. Cal Merle over at EM and he will hook you up with a set.

Everything has its place. You don't need Ultra light/high dollar stuff to turn 7000RPM. Just a decent 4340 crank and rods and forged pistons that don't weigh a ton. The machine work on the motor is far more critical than the componets in it.

If you only plan to turn it 6200RPM you need to step down in the camshaft to something in the 285/290 advertised duration and 235/240@.050 range. Ego or not that big camshaft you have now is going to be a dog below 4000RPM and not really pull hard until 4500 or so.

Anyone who dosen't want you to keep the EFI, just doesn't know what it is really capable of. Me a alot of other people are still running the stock computers and making way more than 500HP. Lots of oval track engine builders get in a rut of building what they know and dismissing everything else. I know all about it. I built those engines for years and my father still does. Since its going be well past my lifetime when local late model guys are finally running EFI, I have come to the mindset to just let them remain ignorant on it. ASA and CASCAR are the only people I know who even bothered to try EFI out. But look - Just because your machinest and engine assembler dosen't know about EFI dosen't mean it won't work. Trust me it will. All you need is someone who knows what they are doing with a Dyno Jet (Chassis Dyno) and Tuner Cat or LT1 Edit software.
Will

 

Very good, will update after dyno tune... ...just finished installing 8 AR473's.

Thanks
BB

 

Well, we are going back though the compression calcs... looks like we are actually @ 12.2:1 Anyway... Car was very lean as predicted...
Any way 1st pull with no changes to ecm 290 rwhp...major knock retard @ 3400 -- prob from lean condition.. Not sure what the tuner did to correct this(i think it was adjustment to cyl size and inj lbs per hour and MAF table) After 7 pulls and 4 hrs to 347 rwhp @ 6200... No more than 31 degr timing @ 100 MAF. rwTq 321 @ 3500 - 4500. I guess cam / compression and pump gas with stock intake 58mm BBK but intake not drilled for 58mm????
Have base and pull 6 and final ecm files and tunercat software to look at anything you want to see. I guess the intake to 58mm so that the 58mm bbk can move more air is the first. Also, I might be stuck with the 31 degree advance (29 above 4000) unless I purchase the 107 octain from the Pressley boys in AVL or 100LL from AVL FBO... for off rd use only right (I think I can since I'm a card toting USDOT FAA certified and do another pull or two... that fuel is 4.29 gal $$$ )
Any thoughts?

 

Camshaft has too much duration. Cam's two sizes too big.

Recent tests on a 383 made over 500 HP using NON competition ported AFR 195s. Ported TrickFlows made close to the same power. The other three sets of heads used in the tests made power in the 480/490 range.

All results were obtained using Comp's XFI 230/236 @ .050 cam on the same short block, same dyno. Comp's XFI 280.

Jake

West Point ROCKS!

 

With mostly stock LT1 heads, 340RWHP is about all it's going to make.

As for the low timing advance. You didn't specify what the quench was and how much clean up work was done to the combustion chamber. Still with that much SCR and all the retained heat in the combustion process from stock exhaust manifolds... 30ish* timing advance is probally all it will stand.

Aftermarket heads have a far more efficient combustion chamber and long tube headers will scavenge the cyl much more efficiently. There is alot of power to be had in these 2 items.

Most good running stock LT1 6spd Corvettes dyno in the 260-280RWHP range. The stock cyl heads just won't support very much more than that without serious port work.

Fix the mis-matches in your combination and the power will come. No need to go running Av Gas in it trying to mask the problems.
Will

 

Thanks for the encouragement will start shopping for the heads & headers.

b

 

if you're going to do ported heads, check out advanced induction. i have a set of their ported stock heads and they look awesome. www.advancedinduction.com

they can also grind you a custom cam to match the heads...

 

Hi all,
Just wanted to update on the LT1 383 XFI292 combo.( I had said 468 but it is comps XFI 292 -- for FI LT1 -LT4)
1. Installed Shorty headers. SO exaust is fully open headers, x pipe and out the back. ...Loud... (would these open chanbered 3" mufflers I see at the car shows tame the sound without hurting performance as they claim?)

2. Bored out intake front for the 58mm BBK.

3. Replaced two bent lifter rods on ( caught this on close re- inspection, originally valve job missed the 588 579 lift; as stated before went to beehives as cam card suggested, some how missed two bent lifting rods from coil bind, engin assembler late night..>>>????). With bent lifting rods did 347 RWHP. Yes I'm lucky....

4. Went back to stock 1994 LT1 oil pump.(another post)
Other notes:
Idle set at 975.
Rev. limiter to 6500
Tweeked tune with tunercat.
Back to Mustang Chasis Dyno.

Results: Mustang Chasis Dyno.
438 RWHP @ 6500 ON computer rev. limiter... not ready to go higher.
Estimated 500 hp at flywheel but what does that matter.
378 RWTQ @ 5500
Note: only at 250 RWHP @ 3500 (somone predicted that)
Have data master will play with tune normal driving.
Still rich at idle and street driving. Leaning out up top.... but no spark knock,,, i think I'm just out of injector.

Timing @ 975(idle) = 18 deg (closed TPS) KPA still high @ 55-60
Max advance = 36 all in @ 3600

Looking at 36lb injectors next.

 

That's hard to believe if not impossible with stock heads.