Down on truck engines?

[emeraldlion]

Okay so I've been reading through most of the threads that pertain to swapping the lm7 and lq4 truck engines, and I've read more than once where someone was averse to the idea of putting a "truck" engine in a sports car. I don't quite understand what would make these engines especially the lq4 any less desirable than the ls1 other than the extra weight from the iron. Is it just that the cam is spec'd for the low end? A simple cam swap would fix this. If this were the case the ls2 would be out as well as any of the older bbc race engines. I mean an l88 would then be considered a "truck" engine, and the l88 is a MEAN engine. Maybe someone could shed some light as to why individuals would not look favorably on the lq4 and lm7 engines. With the price difference they seem to me to be the only way to go unless you have endless dough to blow.

[blueshark123]

Okay so I've been reading through most of the threads that pertain to swapping the lm7 and lq4 truck engines, and I've read more than once where someone was averse to the idea of putting a "truck" engine in a sports car. I don't quite understand what would make these engines especially the lq4 any less desirable than the ls1 other than the extra weight from the iron. Is it just that the cam is spec'd for the low end? A simple cam swap would fix this. If this were the case the ls2 would be out as well as any of the older bbc race engines. I mean an l88 would then be considered a "truck" engine, and the l88 is a MEAN engine. Maybe someone could shed some light as to why individuals would not look favorably on the lq4 and lm7 engines. With the price difference they seem to me to be the only way to go unless you have endless dough to blow.

 

The aluminum blocked motors are lighter and mod for mod produce more power. Not a significant amount of more power though to warrant picking it over a truck engine. It all comes down to budget. I would have went with a truck engine if I were going boosted and didnt have the cash for an LS1

[sq_creations]

It depends on your goals ultimately. The lq4 has larger cc combustion chambers that yield less compression so that is why they make less power. I wanted a lq4 for that exact reason and the iron block is a lot stronger so I could throw boost at it.

[emeraldlion]

Right I understand the benefits of the iron block for boost applications. I also understand the drawback of the iron block as far as weight penalties. Which are all good points obviously depending on a person's specific application. The couple of posts I had read it was brought up why someone would want to put a "truck" engine in the car that made all it's power down low. I thought maybe I was missing something, guess not.

[FlatBlack]

Right I understand the benefits of the iron block for boost applications. I also understand the drawback of the iron block as far as weight penalties. Which are all good points obviously depending on a person's specific application. The couple of posts I had read it was brought up why someone would want to put a "truck" engine in the car that made all it's power down low. I thought maybe I was missing something, guess not.

 

Might want to read through this:

 

http://www.jagsthatrun.com/Pages/Datsun_Z_V-8.html

 

IIRC, I remember them going through the drawbacks/advantages of a Gen 1 SBC, which would apply to what you are talking about [iron vs. Aluminium]. The SBC isn't that much heavier than the L6, and with the setback kits, the weight distribution does not suffer much.

 

My friend has a 92 RS Camaro, he's building a "faux LS3" out of an aluminium block truck engine. [i think it's a L98 6.0L?] There is nothing wrong with "truck engines" IMO. Hell, all Z motors have been "truck engines." VG30, VQ35, etc.

Edited June 9, 2010 by flatblack280

[SUNNY Z]

www.ls1tech.com

 

Read up my friend.

 

IIRC, the iron blocks are ~80 lbs heavier than the aluminum. As for differences in power, there aren't really any. Cube for cube, mod for mod, generally speaking.

[JMortensen]

Right I understand the benefits of the iron block for boost applications. I also understand the drawback of the iron block as far as weight penalties. Which are all good points obviously depending on a person's specific application. The couple of posts I had read it was brought up why someone would want to put a "truck" engine in the car that made all it's power down low. I thought maybe I was missing something, guess not.

I can tell you that the 5.3 in my truck (2006 GMC 1500, so it is an aluminum block) is done by 5500 rpm. I think a cam swap is necessary if you want to get the rpms up higher than 5500 and then you need all the BS to go along with that (pushrods, valve springs). So if you start with an LS1 that might be a better platform if you want to put it in a car.

 

I am going to run in X Prepared class for autox so the extra .4 liters of the LS1 would cost another 80 lbs in weight which is pretty substantial, so I went with the 5.3 truck motor. If they made a 4.8 with an aluminum block I probably would have gone that way.

[scorpio516]

Another "problem" with the truck engines is that the intake manifold won't fit under a stock hood. IMHO, besides displacement, that is the only "problem" with truck engines

[emeraldlion]

Not that the rest of the posters didn't offer up decent information but mortensen offered the response I was hoping for. His experience with the motor being "done" by 5500 sheds light on the comments I read. I knew about the intake being taller the oilpan being deeper I was NOT referring to gen I or II SBC or lt engines but thank you for trying to steer me in the direction you thought I was taking. Again I appreciate everyone's replies.

[jc052685]

It depends on your goals ultimately. The lq4 has larger cc combustion chambers that yield less compression so that is why they make less power. I wanted a lq4 for that exact reason and the iron block is a lot stronger so I could throw boost at it.

 

 

Not sure why you would be scarred to throw boost at a LS motor. Local shop twin turboed a LS2 c6 automatic vette. Motor and tranny all stock. Made over 640whp on 10 or 12 psi.

 

Edited June 10, 2010 by jc052685

[77turboz]

my 5.3l l33 out of an 05 silv 4x4 is rated 310 crank stock and the 99 ls1 was rated 315hp. I realize that GM overrates and underrates, but with the non ls6 intake the power difference is minimal. And my long block was $600 shipped....... Beat that ls1 guys.

 

on another note, my car ran a 12.97 with my one wheel starts. pretty nice for a bone stock motor.

[Cable]

Is it just that the cam is spec'd for the low end?

 

'01-'06 LQ4/LQ9 6.0 use the '01-'04 LS1 cam from the factory. LQ4/LQ9 aluminum heads are the same as LS6/LS2 heads except the chamber is bigger.

 

The aluminum blocked motors .... mod for mod produce more power.

 

That is complete BS. Who told you that?

 

 

As for differences in power, there aren't really any. Cube for cube, mod for mod, generally speaking.

 

Agreed.

 

 

If they made a 4.8 with an aluminum block I probably would have gone that way.

 

That's easy enough since 4.8 and 5.3 share the same bore. Just find a 4.8 and steal the crank, rods, and pistons and bingo: aluminum 4.8.

 

 

Another "problem" with the truck engines is that the intake manifold won't fit under a stock hood. IMHO, besides displacement, that is the only "problem" with truck engines

 

That is an extremely easy fix and not enough to warrant buying a completely different motor in most cases.

 

I knew about the intake being taller the oilpan being deeper.

 

Unless you got an LS1 from a '98-'02 F-Body or a '05-'07 Corvette, you are going to have to change the oil pan anyway.

[emeraldlion]

Thanks for the cam info on the lq4 cable. This kinda clenches my plans. I didn't realize the lq4 used the same or similar cam specs(hadn't paid attention to it really). I've look at what it takes to swap the truck engines and I will be running the gmpp or edelbrock carb intake and carburetor instead of fuel injection so I'm not too worried about intake height variance or the water pump/balancer differences. I had planned to replace the water pump when I swap it anyways(peace of mind thing).

[SUNNY Z]

No sense in fixing what isn't broke. Those water pumps are quite reliable. I've seen many with 150K + on the original.

 

If it was cam specs that was a deciding factor for you, I have a 2002 LS1 cam that I'd almost give you. Big name used cams (vindicator, MSx) can be bought for only a couple benjamins, in good shape.

Edited June 13, 2010 by SUNNY Z

[emeraldlion]

Well yes and no it was the came. I couldn't figure out why someone would be down on the "truck" engine just because it was from a truck and not a corvette or camaro. I understand for autox or road racing apps the extra weight is a big thing, but for a fun weekend car an lq4 would be a blast. I was thinking maybe they had rv spec type cams in them or something that cause the engine to be low end monsters but if the heads flow and they have a ls1 specd cam then other than the weight penalty there shouldn't be anything wrong with it(which was the assumption I was leaning towards). I appreciate the comment on the water pumps. I'm used to just changing stuff like that out when I pull a motor or by a pulled motor but I'll take it under advisement. I agree I'd love to save the 150-200 bucks and not replace it to start off. I'm a very leery individual when it comes to things like that though.

[Cable]

I was thinking maybe they had rv spec type cams in them....

 

Wow, that is a term I haven't heard in awhile .

 

The cheapest cam upgrade in most cases is getting a '02-'04 LS6 cam, springs, and pushrods. They can usually be found for under $150-200 for everything and offer a decent gain without losing the velvet smooth idle.

[emeraldlion]

While I don't exactly expect the velvet idle with the carb swap, I'll definitely keep the ls6 cam swap in mind. For a couple hundred it can't hurt.

I love this chevy v8 pricing. I'm coming from modifying honda engines at that crap is wildly expensive for quality performance stuff.

[zgeezer]

If you are building a smog legal California car, you can't use the truck engine. Period. Not permitted: no truck engines in passenger cars. The referee will catch the iron block immediately; so you won't be able to disguise the truck origins unless you have an AL block.

 

 

If you are using JCI's kit to install the GEN III, and expect to use his a/c kiet, you will have to convert the accessory drive to an LS1 configuration because the JCI A/C adapter does not appear compatible with the truck accessory drive. Just another expense and not an insubstantial one.

 

On the other hand, 4.8 and 5.3 truck engines are really cheap, particularly the smaller 4.8. The money you save on the purchase price will free up funds to invest (throw at) other aspects of your project car.

 

Again, depends upon your design parameters. What do you want? I started with the idea of building a quiet, good handling, stock appearing, classic that would run 105mph and low 13s in the 1/4.

 

All my brother's computer programs said that could be accomplished with a 4.8, an ls6 cam, good tune, and long tube headers.

 

At the end of the day: it is probably a price thing. How cheap can you get the truck engine.

 

G

 

 

[Cable]

While I don't exactly expect the velvet idle with the carb swap, I'll definitely keep the ls6 cam swap in mind. For a couple hundred it can't hurt.

I love this chevy v8 pricing. I'm coming from modifying honda engines at that crap is wildly expensive for quality performance stuff.

 

May I ask why you are planning on going with the carb setup?

 

As far as the LS6 cam, make sure its a '02+ and not the earlier (smaller) version.

 

 

If you are building a smog legal California car, you can't use the truck engine. Period. Not permitted: no truck engines in passenger cars. The referee will catch the iron block immediately; so you won't be able to disguise the truck origins unless you have an AL block.

 

Correct. I helped a buddy put a iron block LM7 into a 3rd Gen Camaro that needed to certified by a referee in California to be SMOG legal. I warned him about the 'truck' engine, but he did his best to make it look like an LS1 with all the accessory drive, intake/rails/injectors/TB, from a '98 LS1, he even rattle canned the block with an 'aluminum' paint.

 

When we went down to the ref, the first thing he asked is if he used a 'car' aluminum block or a 'truck' iron block. Stupidly, my buddy lied and the ref went into his tool box, came back with magnet on a telescoping pole and placed it against the block. Of course it stuck to it and it was game over while wasting the cost of the inspection and the ref made some kind of footnote on the VIN in the computer as to having an iron block incase he tried going to another ref.

 

If you are using JCI's kit to install the GEN III, and expect to use his a/c kiet, you will have to convert the accessory drive to an LS1 configuration because the JCI A/C adapter does not appear compatible with the truck accessory drive. Just another expense and not an insubstantial one.

 

Kwik Performance offers a A/C compressor mount kit (high passenger side mounting location) to work with the truck accessories for $197.

 

On the other hand, 4.8 and 5.3 truck engines are really cheap, particularly the smaller 4.8. The money you save on the purchase price will free up funds to invest (throw at) other aspects of your project car.

 

I've always found 5.3 cheaper than every other LS series, but I am sure it varies from area to area. 5.3's are made 2.5x more than every other LS series (4.8, 5.7, 6.0, 6.2, 7.0) COMBINED. So it makes sense why they are usually easier to come by.

 

 

At the end of the day: it is probably a price thing. How cheap can you get the truck engine.

 

G

 

Agreed.

[emeraldlion]

That's some good info I hadn't come across yet guys, thanks. Especially on the a/c stuff. Around the dallas area 5.3 are goin 500 and the lq4 are going for about 900. I'm one of the fortunate that lives in Texas and this great state doesn't care what you do to your car. 25 years and older only have to pass safety inspection. As far as 5.3 vs. 6.0 I really have no preference figured get the most displacement you can afford and the weight difference b/w the two seems to be negligible considering the extra .7 displacement. The aluminum block 5.3's seem to be fetching a premium over the iron blocks. As far as carbs go I'm more familiar with them (go with watcha know) and cleaning up the wiring is a BIG positive for me. Plus I really like the old school look of the carbureted engine bay. I'm going for a blend between muscle and sport here. I would have gone sbc but the engines don't seem too much cheaper and the extra setback of the ls is always a plus.