turbo charged 3.4 dohc....430 rwhp!

[NateD4]

Slappy you are right on the valve springs and lifters. I'll bet the valve train has a natural frequency above 650 Hz and is more then capable of shift at 7500-8000 RPM.

[FerrariFan]

Nate,
Thanks for the tips. My ultimate goal is to have an engine that I can romp on occasionally without worrying about something breaking. I had limited it to 12 psi without any problems but I babied it most of the time. Your probably right about the rod bolt upgrade. However while it's apart I think I'll go ahead and take it to the next level with sbc rods and custom forged slugs so I can run the max 15 psi the 2 bar map $8f will be capable of. It should be able to run more aggressive timing and get more power. this engine won't be raced or held at high rpms for extended periods of time. Just the occasional full throttle run up through the gears.
The engine has been crated and in a warehouse for who knows how long before I bought it a couple of years ago. Since then it's been sitting in my unheated garage so I'm sure it's been though a few seasons of hot and cold.

FerrariFan what are your goals for the next build?

Unless you are trying to push extreme RPM or plan on hanging at high RPM all you may need is a rod bolt upgrade (if that) and some race alloy main bearings (perhaps a high eccentricity bearing). If you plan on adding more power you may want rod upgrades and custom pistons and a better crank.

I do recommend custom pistons to get a piston properly designed for your application even though they are somewhat expensive.

Also if your new crate 3.4 has never been run, I'd consider running it for a few thousand miles to heat cycle the block so when you tear it down to rebuild the block has been stress relieved and will have a minimal chance of stress relieving after the build up.

Where was your crate engine stored? Sometimes if they have seen summer/winter storage the hot and freezing cold can thermal cycle the block. However if that has happened you'll want to inspect for condensate surface corrosion on things like cams and valves prior to throwing extreme power to it. I'd probably still run it stock a few thousand miles though.

[NateD4]

FerrariFan,

The reason I mentioned running the block is because there is a slight chance that the castings have not been stress relieved fully. About 10 years ago we had a 3.1L that warped the block after an over heat. It required the heads and block to be machined flat again. The old racing thought on this one is that its better to get all the stresses in the block relieved before investing in machining them. I'm sure some might argue that blocks should be stress free from the factory, however my experience and those of people I know in the engine building circle is contrary.

As for the rods, there is a math formula that takes your stroke and rod length to calculate the acceleration of the piston pin which can be translated into a force load if you know your piston assembly total weight and the upper half of the rod.

I'm working on a build that I plan on running up to 8500 RPM. So I did a preliminary analysis of the bolt clamp loads required to keep the rod together. For the most part the only time the rod bolts see load is when the piston is decelerated at the top of the bore. In my case the inertial loads were about 3000 lbs while the compressive loads from the turbo are estimated to be nearly 18,000 lbs in compression. Which means the rod bolts won't be taking much if any of that load.

With that said you only need rod bolts strong enough to handle the max RPM you plan on running (and any over speed allowance you give for missed shifts or lack of traction etc..). The rod strength for turbo is then a requirement of buckling loads due to compressive forces pushing the piston down.

If you are looking for a set of rods, I had a set of 60 degree V6 Carrillos listed for sale last week on e-bay. These are 2" journal long rods to the stock 60 degree width. They also have 7/16" SPS CARR multiphase steel cap screws rated to at least 250KSI (comparable to ARP Custom 625+ cap screws). The guys at Carrillo told me they are virtually indestructable. They use stock width 60 degree bearings. If you're interested PM me. The only reason I'm selling them is because my new crank has small block rod widths (which is really weird) so I needed actual small block rods to properly fit it.

As far as pistons go customs are probably a good idea, perhaps not required, but I'd rather know I have good parts than blow something up. Have you shopped the custom piston makers yet?

[TGP37]

If you aren't wanting any more power, you are wasting your money on a forged bottom end. Get the ARP rod bolts in and HD bearings. Don't bother with the springs or lifters if you aren't looking to squeeze more RPM or boost either. Just rod bolts, and bearings.

That is exactly what I did. Bottom end is stock except for ARP rod bolts, stronger bearings, stronger rings and a crank scraper. Been running 8-12psi for a while now, occasionally hitting 15 max from creep and mbc fine tuning.

The bottom end is pretty strong for stock and the pistons can handle a good deal heat....just do NOT hit detonation, they shatter.

[FerrariFan]

That's what I'm going to do. Stock crank but forged rods, forged pistons, HD bearings and ARP bolts on the bottom end. That way I can run 15 PSI all day and not worry about it.

[Dave96z34]

I think your over thinking it yes having forged rod and pistons would be a good thing or possibly a nail in the coffin. That may or not go as planned. My sc LQ1 has done 48k miles on at 8-9 psi on a engine that's that now has 196k miles. I drag race it weekly in bracket with 30-50 other cars and way over 200 passes. Iv beaten the hell out of it in the proses granading 2 trans in 3 weeks time. Took 1st between the failure weeks A huge plus beats being towed home. Way I look at it my last comp test I did was normal and the only thing im having issues with is failed valve seals. You spun a bearing it happens get another short block or long block. The Lq1 is a tank you didn't bend the rod, shatter a piston or blow a head gasket. Day you break a rod I will be shocked. But I do agree under boost 6k is a better rev limit ARP bolts and a soft rev with a MSD would be help full. Also keeping a spare engine wouldn't be a bad idea but mines been siting untouched for almost 5 years when I yanked it from the donor with 85k. Time to start building another car with that one.

[TGP37]

Dave96z34 speaks good advise.

The connecting rods you have are strong compared to other stock motors. I too would be shocked if you bent/broke a rod with anything under 15psi. The crank is also strong and will handle the abuse. The pistons, well, if you have a great tune they will hold up to the boost. They are hypereutectics and shatter under detonation, they wouldn't last long in boost with excessive knock. But if you tune well and the knock sensor is working well you should not worry about that either.

If you have the money to spend, forged pistons are nice. But if you want to save some $$$ for other mods and plan to stay under 12psi, the bottom end will be fine with the addition of arp rod bolts & stronger bearings. I run hyper pistons, stock rods & crank and had hit 12-15 psig range often, 8-9 psi steady over a year. The only warning I have with hypers is using a ring with tight gaps. If they butt, the piston is gonna rip apart. Though I feel that is only a real concern with fresh rings and LOTS of heat.

in short: the bottom end on these motors are good enough for 8psi all day everyday for years, if taken care of properly. Stock rods and crank will handle 15 psi, though I would want forged pistons at that amount of boost.

[FerrariFan]

I think your over thinking it yes having forged rod and pistons would be a good thing or possibly a nail in the coffin. That may or not go as planned. My sc LQ1 has done 48k miles on at 8-9 psi on a engine that's that now has 196k miles. I drag race it weekly in bracket with 30-50 other cars and way over 200 passes. Iv beaten the hell out of it in the proses granading 2 trans in 3 weeks time. Took 1st between the failure weeks A huge plus beats being towed home. Way I look at it my last comp test I did was normal and the only thing im having issues with is failed valve seals. You spun a bearing it happens get another short block or long block. The Lq1 is a tank you didn't bend the rod, shatter a piston or blow a head gasket. Day you break a rod I will be shocked. But I do agree under boost 6k is a better rev limit ARP bolts and a soft rev with a MSD would be help full. Also keeping a spare engine wouldn't be a bad idea but mines been siting untouched for almost 5 years when I yanked it from the donor with 85k. Time to start building another car with that one.

Wow, that's an impressive amount of flogging on that high-mileage engine! Give's me hope that I'll have many trouble-free miles when mine is done. I'm of the mindset that as long as the engine is getting yanked why not over-engineer things while we're at it. I'm not adding nitrous or a bigger turbo just a few more lbs of boost. I like your idea of the MSD ignition to add a soft rev-limiter.
By nail in the coffin are you referring to adding stress to other drivetrain components like the transmission? I'm running a 282 5 speed now. I've heard that they're pretty tough. As long as I don't run slicks, the rear tires are the fuse that will burn-out (spin) before any drivetrain components hopefully.
I like your comparison of the LQ1 to a tank. Let's take the analogy a bit further. If you've ever looked at military hardware compared to civilian stuff it's over-engineered and sturdier than it needs to be to survive a lot of abuse. The down-side is that it's a lot more expensive than similar civilian components. Who cares if it's not your money right? LOL
My plan is to take this M60 and turn it into an M1. How can that be a bad thing?

[3400-95-Modified]

You make it sound like nitrous is worse... lol, I've been running that since around 06, started with a 50 shot and quickly went up to a 100 shot... I've yet to have any issues running that on a fully stock 3400 bottom end(first engine was a standard rebuild done by me nothing special at all). Just two years ago I did Clevite bearings in my 05 3400 and thats it at the time it had probably 35-40k on it, I should probably move to ARP rod bolts but I didn't think it was necessary, since I have yet to blow a piston or spin a bearing, all my stock bearings came out looking brand new.

[RedZMonte]

I have put ~75K Turboed miles on my DOHC all stock 8psi and beat to piss... She sees Red line quite often.. My valve seals are toast from sitting so long and my front HG appears to be starting to leak a little. I cant complain the car now has 165K miles (turboed at 90K miles). Hell my stock 4T60-E lasted to 130-140K Miles before it broke (~50K of it turboed) which is awesome even for a stock LQ1

S

[FerrariFan]

You should have no problem at 8 psi-12 psi. I have a Greddy boost controller and the "low" setting I have set at 8 psi and the "high" setting was 12 psi. I mostly drove it on the low setting and the high setting was only for occasional use. It ran great like this for two years. For whatever reason I decided to crank the boost up a few notches and I saw 15 psi on the boost guage and it was pulling like crazy! It was totally awesome until I got home and heard the rod noise at an idle.
Anyway, the lesson here is don't get greedy and just be happy with what you've got. Yeah right!

[Dave96z34]

Nail in the coffin as in you have more problems you were not expecting. Stock bottom end can take a beating with a proper tune. more later its time to drink

[NateD4]

It's really a toss up when we start talking rods. The stock rods have proven to hold up for many people. The stock rod bolts are probably fine if you keep the RPMs down. If you know the pistons weights you are looking at you can calculate the rod bolt loads based on your intended RPM range. For most people stock bolts are probably ok and ARPs make things safe.

IF you plan on really cranking the boost up you will want a different than stock set of rods for buckling resistance and detonation resistance.

You really have to define your reliability requirements and rebuild mileage. It is possible to make more then 500 HP on a stock bottom end, it may only last a few minutes or hours depending on how you run it.

Back in Corvette C4 days a few of the well known tuners (mainly Greenwood and Callaway) were messing with turbo chargers. I read an article that discussed the difficulty they had making a stock GM small block reliable. It mainly had to do with bottom end components. These engines had forged bottom ends because thats what it took to make them last. I think most of that discussion is valid today... however technology has improved.



TGP37 what do you mean by stronger bearings? More clearance? Tri-metal vs Bi-metal? or are you talking full race bearings?



FerrariFan, I agree on over building it. I guess it depends on your budget, patience and what you want out of the engine. In my case I've decided to put the best I can in it. I personally would rather be able to drive an engine and not worry about whether I can flog it. Now the transmission is a different story...

In terms of bottom end, there are three things to be careful of. Boost, Detonation and RPM. Any of these can wreck a rod if it is extreme.

[robertisaar]

http://www.kitcars.com/Classifieds/AdDetails.asp?classified_id=23338

came across this while trying to google for kit cars.

[FerrariFan]

Yep, that's my car. I can't sell it with a bad engine though.