Hello All,

Is is possible to build a 408(LQ4 or 9 Block) longblock for under 6k? Looking for a good streetable motor(450-500rwhp through an M6) with either LS6 port heads or L92/LS3 heads.

 

you could probably pick up some pretty stock ls6 heads cheap and keep your cost down. Are you talking 6k total? There are lots of little things that add up.

 

Yes, I was looking to stay under or around 6k for the entire longblock

 

Its possible. But unlikely if you want everything done right.

 

Yes, it's possible if you reuse your existing intake manifold and related parts, go with a more budget-friendly set of heads like the PRC stage 1.0 LS6 heads, and don't add any upgrades to the build. Building the setup for 450+ RWHP would be easily achievable with a build that isn't very radical. This is assuming you already have induction, long tube headers, and the other corresponding bolt-on mods. Feel free to give us a call, and any of our sales guys will be more than happy to discuss your options with you. We can also put an itemized estimate together and email it to you so you can see exactly what you're getting.

Trevor
Texas Speed and Performance

 

You really don't need a $6K 408 longblock to make a 450-500 rwhp street engine from a 6.0L iron block truck engine. Heresy? Perhaps, but here are some thoulghts:

A 408 is only 12% larger than a 364 (stock 6.0L). If both a 364 and a 408 have about the same top end (heads intake), the 408 will be hard pressed to make 12% more hp than the 364. It may well make 12% more max torque, say about 50 lb-ft more, but at what cost?

A stock (used even) 6.0L LQ4 with a rod bolt upgrade is good for well over 7000 rpm (which you won't need to spin to get your hp goal). Block and rotating parts are not hp limited in these engines until lots more than you want, and it's rpm that loads the crank and rods, not NA power.

So, buy a used LQ4, change the rod bolts and spend your money on the L92 topend. You may want to change bearings and rering it, but many 50,000+ truck LQs don't even need that. This may fly in the face of "conventional" thinking, but it is working well for a number of street and race engines I am familiar with. GM did a really good job on the OEM longblock.

Your choice of who does the L92 heads and what all they need is critical. Some folks do L92s very well and a fair number don't do much to help them. Some even hurt them probably because they don't understand how/why they work well.

As for valvetrain, stock lifters, rockers (perhaps with a Comp or other trunnion bearing replacement) and valves will work. Your valvetrain person might go for lighter steel intakes. Not a bad idea as they reduce the spring loads required to maintain valvetrain control. The cam needs to be matched to the application and especially to the springs, retainers and pushrods. Think light on the springs and retainers, and big and beefy on the pushrods.

If you have a decent LQ4 longblock, you might reach your goal for the $6K total cost, not the longblock/shortblock cost you mentioned. At least spend half of the $6K on the top end.

To paraphrase a quote attributed to Willie Sutton, the bank robber: "Why spend your money on heads? Because that's where the power is."

Good luck.


Jon

 

Here's what I have in mine so far
Lq9 used engine-600
L92s heads-800
Studs main/head -400
Carb intake 400
Stroke kit tsp 402ci-2100
Cam 400
Valvesprings-200
Block hone-250
Conversion flywheel-400
Msd6010-350
Total-5900

All prices are rounded up. This is what I have in my motor so far. Long block can definitely be done for under 6000. I pretty much built the whole engine for that much. Granted there's gonna be other costs gaskets brackets bolts etc. But it can definitely be done. Of course you save a ton by doing the work yourself and buying used parts. Hope this helps!

 

I'm not sure how close you could get. My 402 was a "budget" build in every sense of the word. I bought a good rotating assembly (Compstar/Wiseco) but was thrifty everywhere else. LS3 heads, used LS3 intake, used 95mm throttle body, etc. Based on my spreadsheet, my motor build alone comes up a hair under $10k once you factor in the miles and miles of little stuff, and I still haven't filled in prices for all of the parts I'm going to need yet.

However, my list of "little stuff" is a lot bigger than most because I'm doing an LS swap into a thirdgen. If you're putting this stuff into a car that's already got an LS, your pile of "little stuff" would be significantly reduced and I could see your expenses being way lower than mine.

 

Yes, I will be installing this engine into a 2001 Trans Am M6.

 

A large portion of my expenses were related to ECM, harness, exhaust and other installation issues. This also gives you the ability to re-use some of your existing parts for now, like your intake, throttle body, etc. However, even going into that car, you're still facing tons of small stuff like gaskets, head bolts, blah blah blah.

 

My friend got LQ4 motor from auto yard with 317 heads. He figured out to expense on the engine (forged pistons/big cam/carb.rebuild kits,machine shop)for LQ4 around $4,500. He not sure he would do it or sell his LQ4 motor with 4l80e.. I suggest him>>>Play around to check TSP/SPCD.

 

We've seen 530+ rwhp on 23X at .050 unported LS3 heads on 408s and the Callies 5140 crank makes it no where near as expensive. You can run tighter LSAs and more cam if you want since you have valve reliefs.

50 foot pounds of TQ down low is very nice in a real car as well and cubes equal more tq until the heads and manifold give up.

Still everything you are saying Jon is correct and you can make a good amount of NA power with the stock GM OEM shortblock. The rings are very low tension and the pistons seal up well and make good power.

The only thing I don't like is the lack of P to V but with the shorter L92/LS3 events it is not that bad and with good valvetrain the parts don't usually crash too much.

NOS or power adders and the stock pistons are not so good so you might as well go bigger then since its not so bad if the entire engine is getting rebuilt anyway.

Also in over ten years of having people build multiple engines I have never heard people say "this engine is just too big and has too much power down lower! I think I will build a much smaller engine next time!"

Just haven't ever heard that yet and in fact they always go the other way and also always go faster and have nicer street rides.

 

Have you also heard, "Gee, it makes all the power I originally wanted and cost a bunch less than I thought it would!"

There is something to be said for that reaction.

If the owner needs to brag on the (stock) shortblock, he can always truthfully say, "I had the biggest LS engine shop in the world do the short block."

Jon

 

Nope never heard that. People always seem to want more power. It's just a matter of time.

The bigger stuff also always makes more power and makes it easier. Been there done that a 1000 times.

Again like you said in econo mode staying stock is always cheaper but that's hardly a revelation or anything.

Any kind of power adder or a seriously larger cam and the stock shortblock pistons go south in a hurry when those glass pistons let go.

Often they take the entire engine with them. Then it's not so cheap anymore.

 

I may actually need to email you guys for some parts as well. Mapping out a engine swapping project....

 

You revived a thread from 2010 to say this? lol

 

I seriously doubt he saw the post dates. No newbie does.....