rklessdriver

GEN1 and GEN II difference is in the opti and cooling system.... rods and pistons all interchange (but the GENII has 1.5mm rings).... crankshafts (1pc RMS) interchange from 86-97.

I don't know why the LTX timing sets are so expensive. Probally has to do with machining cost and the fact that not many people build LTX's these days.

AI's price includes all new springs and stainless valves. I'm 99% sure their included springs will work but it's been a while since I had a set from AI in my hands (used alot of AFR in past few yrs) so all you need to do is give them the specs on your cam.

The AI LT4 195cc is slighty better than the AFR 195 street and slightly worse than the AFR 195 Competition.... it's a good head. Any one of them is great for what you want to do.

I'll be happy to run some Engine Analyzer sims (so you can see the HP/TQ curves) on this excact combo for you.

I do have some results from a bracket car we used this grind in last year. I updated the motor which had a similar grind from REED cams. It picked up 15HP. It's not an LTX but a GENI 383 with WP Motown 220 heads, 11.5 compression, Victor Jr intake and AED 750HO carb. It made 560HP@6200RPM and runs 10.70's in a 3000LB 67 Chevy II.

I used that same similar grind from REED cams in blackharleymans 383 LT4 back in 2008.... His car put down 421RWHP@6300RPM with a bad optispark (missing like crazy past 5500RPM). That car used AFR 195's and only had 10.8 compression so he could run 89 octane gas. Like I said Mikes cam is 15HP stronger across the board than that old REED grind....

Yes Mikes cam will have a nice lick at idle. It'll sound great at idle then clean up around 1500-2000RPM and be very driveable in the higher gears at low RPM.

This combo will run good on a 150 shot. Exhaust duration is a little short for more any than that and you'd be way over the safe HP on your rods and stock crank. Just keep the RPM down. You'll need to open the top ring gap up a little if you might run the bottle some day. the wider ring gap won't hurt anything if never put the gun to it.
Will

merlot566jka

Yes, I would appreciate it if you could run that combo through your sim!

I have contacted AI with pics of the damage and details about my build... awaiting a response.

Also got a line on some AFR 195 eliminator streets, in case my heads aren't going to be able to be repaired.

Those pistons you're recommending, how do I find the weight ? (with out actually buying them) I am leaning towards them, just want more data.

I looked at cruisinartvette's post for his pistons and rods, not sure if I want to buy used pistons. I mean they look great, and I am sure there is nothing wrong with them, but they are a couple hundred more and used. I guess I dont know enough to compare the two and know which is better. I see they are both forged, quality, and will work either way... but whats the difference? Weight? Pin? Rings size? Material?

Thanks,
Jonathan

96GS#007

You need to find out what the injectors flow at a given fuel pressure. Multecs are rated at ~43psi...ie stock LT4 injector flow 28# at 43psi. Ford SVO injectors are rated at 39psi. I'm not sure what the Bosch injectors are rated at. Keep in mind that the relationship between flow and psi is not linear, hence the reason you need to know both.

You *must* also update the tune. Use the AFPR as a way to get the injector flow rate you want. Then update the tune so that you have the driveability characteristics and WOT performance the package offers.

FWIW, on my 383 I'm at ~500chp. My injectors flow 32#. 32# should be a pretty good number for your setup. Peak duty cycle should be ~82%-84% which is right on.

cv67

The piston weight on mine are 420 dont think that includes the pin/locks

It is a high silicon forged piston meaning you can run a tighter wall clearance.

You dont have to buy them just offered it as an option
I understand "used"....still the car was only driven 4 times (60 mi) no racing WOT.
There is 0 wear.

Of course budget comes into play and if you need cheaper than thats what ya gotta do. Its good stuff though, and balanced/matched as a set. You gotta buy whats best for you. Maybe Will can hook you up?

No matter what you get spend 75-100 and have it all balanced (as youll have another crank) anyway EVEN if its advertised as a balanced assy. Trust me on this one, some of the best money youll spend.

merlot566jka

I totally agree. I want this engine balanced completely! Jury is still out on the pistons...

rklessdriver

Here are the specs on the Probe pistons. 506grams. Not bad for stock 5.7 rod pistons (1.560 compression height). Plus the Probe wrist pin is only 118grams... The last set of factory LT4 pistons I weighed were in the 540gram range and the pins were 160grams.

http://www.probeindustries.com/Produ...Show=TechSpecs

Ron's Manley pistons are lighter because the compression height (1.250) is shorter due to the longer 6" rods. The rings are 1/16 as that has been the standard for racing engines for a long time. The Manley is a better piston (it's shorter, lighter &has a better skirt profile) and you get a good deal with the 6" Manley connecting rods which are 100% better than stock (4340 CM material and it has capscrews) - but you have to look at the whole picture and decide what you can afford to do....

I've ran the Engine Analyzer simulation today. Give me some time to upload the simulation screen captures.

BTW - With a 4cc valve relief piston your looking at 11.65 SCR (static compression ratio) with a 54cc head and the Victor 5898 headgasket.... Assuming piston is .020 in the hole on an undecked block. With Mikes cam your looking at 9.12 DCR (dynamic compression ratio).
Will

96GS#007

SRP would be another piston option and is what I used for my 383. For a .030 350 build, you'd end up a touch heavier since you'd use flat tops with maybe -5cc for the valve reliefs. I used 5.7 rods but since mine is a 383, my compression height is different vs a stock stroke engine.

Some of the specs for my setup...

- Forged from 4032 aluminum alloy
- CNC machined with radiused valve reliefs
- 1.425 Compression Height
- -16cc inverted dome
- 457g each
- Double spiro locks
- 927-2750-150 wall wrist pin (130 grams)
- CNC Machined ring grooves that accept 1/16 1/16 3/16 rings

Many, many choices, just have to find what fits the budget and performance goals. Remember this.....far easier to build a better bottom end and swap a cam or heads later than it is to make compromises across the board and then have to re-do an entire engine.

rklessdriver

Here is the EA simulation. Keep in mind that EA is the best simulation program out there but it's still a bit optimistic. The version I use for these free engine consulting gigs is a few years old. It's still a great program and takes alot of time to properly do a simulation. It's just not as time consuming as the EA Pro which also cost so much $$$ that I have to limit use for paying customers.



From what I know about actual dyno results on this cam and similar ones, this is a accurate representation (within 10-15HP) of what you'll have.
Will

merlot566jka

Woah, 9.12 DCR... Thats higher than I thought. Is that still in the 91 octane ball park? Bigger chambers/gasket or should I look for some more duration? I thought the idea is to stay around 8.5 DCR unless you were 200% sure of every absolute detail when the engine is assembled.

80g less than stock, is still satisfying to see on the pistons.

With more compression height on the Probe's, Ron's pistons look even more appetizing.

merlot566jka

Holy geez. That is easily 50hp more than I expected. Looks like a turbo graph the way the hp climbs and the torque swells.

Piston speed !! EXTREMELY!! high. Haha, isn't that the point? But that raises questions about the rods.

I am sold on this combo as per these results. Now to work out the details.

oh and what about the AFR 210's? Looking at the details, and the price, it sounds better than AI's work on my lt4 heads. But I dont want to over lung this engine. They look to be about 20cfm more than what AI can do.

merlot566jka

Options. They are evil.

tpi 421 vette

If you have a 350 turning close to 7000 rpm, I don't think the 210's are overkill. The 195's would probably have better throttle response, but the 210's would probably make a little more top end. If it's in the budget, I would consider the AFR 195 comp port that flows over 300cfm. But that cylinder head is more expensive.

The AI ported LT4 heads are probably in the 205-210+cc port range anyways. The LT4 heads start life as a 195cc head.

rklessdriver

Yep, at 11.65SCR and 9.12DCR your combination is what we refer to as "set on kill".... meaning set up for max hp.

Judging from The race track at Tulsa (619ft above sea level) and Thunder Valley (1165ft above sea level) you guys average across the year about 900-2500 FT of Density Altitude....

That's what about what I average here. 91 octane sucks for sure but it's workable with knock sensors, 160* thermostat and provided you don't beat on it when the coolant temp is over 200*....

My 92 has 11.66 SCR and 9.15DCR, but I do have 93 octane. I follow those rules with my personal car and don't have any problems....

To "take it off kill" and make it absolute safe... Since your either getting Ai to do your heads or buying AFRs the chamber is the best way to take it down a notch. A 58cc chamber would give you 11.06SCR and 8.52DCR.
Will

rklessdriver

Keep in mind these numbers are best case with near racing exhaust, controled air temps ect....

Right on.

AFR 210's... I would not do that on this 355. It's going to soften up the TQ curve a bit and my main worry is that it will extend the RPM range (where it still makes power) a bit too far for this hyd cam.

On an oval track race engine, sure we operate in a very narrow RPM range and big heads work great on short stroke motors.

On a street car you want a broad, smoth TQ curve and that's just what you have from 3000RPM-7000RPM. These sims are using a 206cc port for the AI LT4's. The AFR 195s will have an even broader TQ band ie come on earlier in the range while giving up nothing on the top end. We are talking small amounts thou.
Will

americasfuture2k

I'm merlot's brother... I hope this is a decent enough of a contribution...

Would stepping the injectors up to 36# hurt anything? I come across many of those on my adventures and could round up a set or few up for you to get cleaned, or clean ourselves?

I don't know if the L67 injectors will work or not, but i am assuming they will.
But, if you go to those, will you need to upgrade the fuel pump or does the stock one flow enough for that kind of fuel requirement?

rklessdriver

On the injectors. It won't hurt but there is alot of head room in the FMS 36lb dark blue tops.... I'm over 500RWHP on a set.

On the fuel pump. IMO 400RWHP and beyond you need to start looking at a 255L unit from Warboro or Racetronics.
Will

96GS#007

I have the Pro version and if one takes the time to accurately model the engine, it's very accurate.

MK 82

.300 is 300 thousands.
.030 is 30 thousands.

What a difference a decimal point makes.

I put the CC 503 in my LT4. I like it.

LT4BUD

FWIW, based on the dyno curve this combo begs to be rev'd higher than 7000 rpm to get to the optimum shift point....

and the OP said he was looking for a high rev engine, this is it if it is strong enough

merlot566jka

Last summer in Oklahoma, we saw temps over 105* for over 3 months. I dont think having this car "set on kill" is going to work. Plus with the quality of gas out here varying so much, and the way I drive... this is a recipe for disaster. 57.5-58cc chamber sounds like the best idea.
I do have a 160* stat, and I have never seen my temps above 183*, but this is stock.