Sunbeam Fanatic

Hi all

Stick with me, I'm from over the pond and am usually only used to dealing with 4 pots!

So I'm building my first Hot Rod out of a 1968 Rover P5B Coupe and it usually runs the Buick derived Rover V8 and auto transmission.

I'm going to keep the inside/outside fairly stock but have decided on using an LSx engine, but I haven't decided which type yet .....

And so we get to the first questions:

Am I right that some LSx engines had alloy blocks (as this is my preference)?
If they did which ones (so I know what to look for when buying)?
What's the difference between LT and LS?
Why would you choose an LS1 over an LS2 or LSwhatever?

I need to choose the base engine first then I may need some help on that specific type (re-building, tuning etc.)

All advice gratefully received.

Cheers,

SF

Some LSx type motors would be the LM7(5.3L), LM5(5.3L), LQ9(6.0L), LQ4(6.0L) these are made from iron, but are on a LSx based platform

LTx motors are inferior IMO to LSx motors cause the LS has a completely different platform where they redesigned and significantly improved the valvetrain, and got rid of the distributor, and reverse water cooling system. Lets just say the LS motor is just more effcient than the Iron block LT1.

LS7>LS2>LS1>LS4 <-----Thats IMO.

If you can afford the pricetag of the LS7..go for it.

I would pick an LS2 block over the LS1 block becuase all they basically did was take the LS1 and fixed all the bugs and improved the motor while increasing bore size from 3.8999(3.900) to 4.0002(4.000).


If you want an LS7 type motor get an LS2 block and resleeve it with 4.125 bores and youll have a 427

I can keep going on what type of crank, cam, etc. if you want.

Just PM me with your goals and what you plan to do with the car, and I just might be able to help you more.

3.4camaro

iTrader: (1)

lsx blocks are aluminum
ls1 and ls6 are 346 cubic inches

ltx blocks are iron and 350CI, they are stronger blocks, but dont make as much power as their ls counterparts.

if i were you, i would get a resleeved ls2 block and build the **** out of it. you can easily get 500 hp out of a healthy heads and cam package.

EDIT- i would do resleeved ls2 because its bigger than 346 and can be bored out even more. the ls1/6 blocks can be bored .010" MAX.

and im an english american. be prepared to get some flac for supporting straight line racing over there!!

LS1Formulation

iTrader: (13)

Some LSX blocks are cast iron. They make aluminum blocks in 5.3, 5.7, and 6.0 Liter displacements. Iron blocks come in 4.8, 5.3, and 6.0 Liter. If you're not planning on modifying your engine much, an LS1 would be fine. If you are, start with an LS2. There's a lot more potential in an LS2 because of the 4" bore. Other people can chime in with more info, I'm sure.

DrkPhx

iTrader: (15)

1) Am I right that some LSx engines had alloy blocks (as this is my preference)?
Yes. I would stick with LS1 or LS6 aluminum block because of weight and strength.

2) If they did which ones (so I know what to look for when buying)?
See above

3) What's the difference between LT and LS?
Quite a bot of difference. In fact, they share nothing in common except bore size. Completely different engine architecture and parts are now referred to as Generations.

The years below are based on the Corvette production MY (Model Year) because that is when the engines debuted.

- Original small block Chevy (SBC) 195x-1991 - Gen I (Generation One)
- LT series (LT1 and LT4) 1992-1996 - Gen II
- LS series (LS1 and LS6) 1997-2004 - Gen III
- LS series (LS2 and LS7) 2005-current - Gen IV


4) Why would you choose an LS1 over an LS2 or LSwhatever?
My personal choice is the LS2 because of increased cubes (6.0L vs. 5.7L) and how well it responds to modifications. However, based on your location the LS1 (compared to the LS2) will probably be more readily available including the computer because of higher production. Bottom line it depends on your ultimate goal and budget, but even a stock LS1 makes great power especially in a relatively light weight chassis.

LS1>girlfriend

iTrader: (19)

ls blocks are aluminum
lt blocks are cast iron

DrkPhx

iTrader: (15)

Some LSX blocks are iron; 4.8, 5.3 and 6.0L used in the trucks and SUV's. Even though technically they are not a LS1 block, they are part of the Gen III family and now referred to as LSX blocks.

300bhp/ton

Alright there mate!!!

P5B my fav Rover and the Queens own personal car is a P5B.

As for the engines, well I know price and availability are PITA in the UK. Importing an engine may be your best bet. If you're not already a member I'd take a butchers at www.v8owners.org there's some really helpful people over there.

Now for Lsx engines. Well the LS1 was introduced in 1997 in the C5 Corvette, since then there have been LS6, LS2 and Ls7. There's also a smaller displacement 5.3 litre variant, but honestly don't even bother with it.

ALL Lsx engines are aluminium the only cast iron block ones are in fact LQ engines and are used in GM trucks. Essentially the same engine but with some changes. Having said that the aluminium is proven to handle 1000bhp so unless you plan on Pro-stock or something I would go for the aluminium one.

Over the years there have been several changes to heads, displacement, injectors, PCV system, cam, intake you name it really. The newer the engine the better. But in reality they are all very good and very capable.

The Lt1 and associates is the previous generation engine and is in reality very similar to the original small block Chevy from the 60’s. It’s not a bad engine but it’s heavier than a Ls1 being as its cast iron and doesn’t produce the same HP or respond as well to mods.

LS1, 5.7 litre/346ci 1997-2000 – this had 320-345bhp depending on what vehicle it came from. It uses what is known as the LS1 intake manifold and uses the 853 casting heads. 97/98 are slightly different and for simplicities sake I would for preference get a 1999 or newer unit.

Vehicles found in: Camaro, Firebird/Trans Am and Corvette.

LS1, 5.7 litre/346ci 2001-2004 – this had 325-350bhp. It used the later designed Ls6 style intake manifold and used the later heads.

Vehicles found in: Camaro, Firebird/Trans Am, Corvette, Pontiac GTO 2004 only and Vauxhall Monaro (UK) 2004 model only. There is an oddball UK model the Vauxhall Monaro VXR had what was badged as a 5.7 litre LS1 but was rated at 385bhp, I’m not sure what it had different though.

NOTE: GM’s advertised HP numbers for the Ls1 in the Camaro/Firebird are underrated the engine is essentially the same as a Corvette unit except for exhaust in airbox.

The main difference with a Corvette unit is it has an electronic throttle body whereas the Fbody engines are cable operated. The Corvette also didn’t have EGR whereas the Fbody did. But on a Rover P5B emissions won’t mean anything so you’ll be ripping all that off anyhow.

Do you know whether you are going EFI or Carb? Any of the GM PCM’s and wiring looms would work or you could go for an aftermarket EFI setup such as Megasquirt. GM Performance Parts and a few independents also offer 4 brl carb conversion kits.

LS6, 5.7 litre/346ci 2001-2004 – This engine was designed for the Corvette C5 Z06 in 2001 it had 385bhp and 2002+ it 405bhp. Very nice engine, different block (better oil ways and cooling I believe), higher CR, different cam and heads and valves. The engine was also used in the Cadillac.

LS2, 6.0 litre engine 2005+ - This was launched in the C6 Corvette and is also found in the 2005 Pontiac GTO and Monaro. Essentially it isn’t all that different to the LS6 just with more displacement a different intake manifold and cam. Funnily enough it only produces 400bhp so slightly less than the Ls6 but it does evidently have more tuning potential due to displacement.

LS7 ,7.0 litre/427ci – This is in the current C6 Corvette Z06, it has over 500bhp stock and several chances from the LS2 although still the same engine family. GM will sell you an engine for about 15k but IMO it’s not worth it, a built LS2 will make more power for a lot less money.


Depending on your intent will have a big affect on which to look for. Modified engines really override stock HP outputs and make them meaningless. A LS1 can easily be made to out perform a LS6.

Do you have a HP target at all?

Here’s some guideline HP numbers, they are bhp at the flywheel (SAE):

LS1 5.7/346ci :
-Stock 320-350bhp
-Bolt on 400bhp
-Mild cam bolt on 420-440bhp
-Wild cam bolt on 440-460bhp
-Mild cam & heads and bolt on 480-490bhp
-Wild cam & heads and bolt on 500+bhp

LS6 5.7/364ci:
-Stock 385-405bhp
same as LS1

LS2 6.0 litre:
-Stock 400bhp
-Modified about 10-30bhp more than a 5.7 Ls1

These are all n/a.

Two further possibilities exist.

1. Forced Induction, even a built 5.7 litre LS1 will be capable of a true 600-700bhp on pump fuel. Bigger displacement equals more HP.

2. Larger displacement, all of the engines can be stroked and/or bored to a larger displacement. 383, 402, 408, 427, 454ci and more HP is available from bigger displacements. You can buy these displacements right off the shelf as well.

It may well be worth having a look at pricing up a crate engine or long block compared to buying a used engine. It may turn out to be similar money.

Texas Speed & Performance have a great range but so do many of the other sponsors (-->).

There are lots and lots of different mods available and the LSx engines take to nitrous very well if that was you line of thinking.

Sunbeam Fanatic

Awright!!

That was really helpful thank you! Yes the Queens car, my long suffering mechanic who will be doing much of the assembly has already christened the project as "The Gentlemans Dragster". The plan is to keep a nicely refurbished stock interior (leather armchairs, picnic tables, wilton carpet etc) and exterior but completely re-do the suspension, drive train and engine.

Cost dependant I would be quite happy to aim for 500bhp using re-worked heads, mild(ish) cam over-bored etc. but I need to find good suppliers and do the maths for pricing. Also quite happy to do much of the engine assembly work myself (not the machining).

I would like to keep the injection as it looks like it will really help with under bonnet clearance (as much as I like the look of a bit fat carb or two )

It clearly looks like the ideal base unit would be an LS2 but that would be dependent on price and availability of the base unit.

You are quite right that I can ditch the emissions gear which is a bonus.

I would prefer to keep and re-use stock injection although a bigger throttle body may be necessary.

I'll probably use aftermarket ignition by MSD or similar.

I guess the main question is do I need to budget for stronger engine internals if I am aiming for 500bhp??

Cheers,

SF

300bhp/ton

Nah 500bhp is quite doable on stock internals. If you plan on nitrous then forged pistons and con rods may be advisable.

Personally I like Texas Speed & Performance, they have a great reputation are very friendly (always helped me out when I've had questions) and are willing to ship to the UK.

http://www.texas-speed.com goto either 98-02 Fbody or 97-04 Corvette section.

I'd probably go for a wild cam and some good flowing heads and give a boost to the SCR. Combine this with the normal bolt on's. Here's some of the components I would by for a n/a build on a LS1.

Cam = Texas Speed & Performance Magicstick 4, this is a pretty wild cam but still quite streetable. And on the larger displacement LS2 it will be fine.

Heads = TSP Terminator heads. With the above cam several guys have seen 480rwhp+ with manual trannys. Heads will include valve springs.

On the LS1 this cam and head combo would require the pistons to be flycut. As you'd be having the heads off anyhow I don't see it as much of an issue. I feel the extra hassle of flycutting is certainly worth the extra CR you can gain while still being able to run a big cam.

TSP cam install kt (gaskets, push rods and such)

FAST LSx 90mm intake manifold and P.T.M. 90mm Throttle Body.

Note: The Ls1 has a 75mm TB as standard. The Ls6 intake on the 01+ Ls1's is pretty good really and you can port your own TB (link in my sig). But a FAST 90/90 combo will still see 15-25rwhp more depending on setup.

The LS2 is 90mm straight from the factory. You can port the stock 90mm TB to good affect but again the FAST 90 intake manifold will still show HP improvements but I'm not certain by how much as I've never looked in the LS2 engine much.

ARP 12 point head studs - Wild cams require higher rpms. 6700rpm is common for a big cam but you'll need the head bolts.

Injectors - With a big cam and decent heads you'll probably need some beefier fuel injectors TSP offer several setups. I think the stock fuel pump should be ok though.

TSP ported LS6 oil pump - This is better than the LS1 oil pump. Not too sure what the LS2 has it might already be a LS6 pump as stock equipement.

Intake - I'd be tempted to make a proper free flow cold air intake. It'll have to be custom to fit the Rover but worth while. Fbody's usually run a replacement lid to the factory airbox, this is good for a claimed 10-15rwhp. FTRA (Fast Toys Ram Air) is a ducting system that takes air from outside the car, I also think it plays a role in air box resonance. Either way people have consistantly seen lower air intake temps and ran 0.2-0.3 thenths quicker at the drag strip and 1-2mph increase with just the addition of the FTRA, use Google to find the retailer for it.

Rollmaster Double-roller adjustable timing set. It's not expensive and worth the extra saftey and adjustability.

ASP harmonic balancer crank pulley. I guess it depends on what accessories you run such as air con, power steering and such. But a pulley is usually a good mod.

Ls1 adjustable belt tensioner - this is an inherant issue with the LS1 and the belt tensioner is just a precaution more than anything.

I'd be tempted to use poly motor mounts. The OHV engines can rock about quite a bit espcially with a big cam.

Tuning - If you stick with the GM PCM I'd look at getting EFI Live or HP Tuners. They allow you to tune every aspect you can think of. The hand held tuners are rubbish and I'd avoid them.

From my research I reckon a pretty mean h/c bolt on Ls1 or LS2 can manage about 95bhp/litre and still remain streetable.

That means potentially:

LS1 5.7 litre at 95bhp/litre = potential HP 541.5bhp
LS2 6.0 litre at 95bhp/litre = potentail HP 570bhp

So both engines offer good performance.

Most people seem to reckon that the LS1 can easily handle a 100 shot of nitrous and many even spray a 150 shot on stock internals. If you went for forged pistons, con rods and better piston rings then there's no reason a 150 shot couldn't be used safely giving a potential 680-700bhp while on the juice plus good street manners, good reliability and potentially 22-28mpg!!!!

I'm sure I've missed many parts out. If you want to PM me your email address I can send you a copy of my build/parts spreadsheet. It's got prices, reatailers, part numbers and exchange rate/VAT conversions on it plus other random info.

Any idea on what sort of transimission and rear end you are going to use?

With the wilder cams they like lower final drives (numerically higher). On an Fbody with a T56 6 speed manual most would probably go for 4.10:1 final drive gears. Although I guess the tyre diameter will affect the decision a bit.

Almost forgot, long tube exhaust header manifolds. These are a must really for high n/a HP. Since being on this website I've learnt that headers are about scavenging more so than flow.

Stock manifolds flow quite well and even work well on boosted motors. Shorty headers look nice but offer next to no HP gain over stock for n/a. This is because they don't scavnege and the increased flow rate really isn't needed for n/a setups.

The only answer is long tube headers (long primaries). I doubt if any Fbody or Vette ones will fit the P5B. I'm also not sure how much room you have or whether you could re-route the headers thru the inner wings like on the MG RV8. Regardless I would seriously consider having some custom long tube headers made for the car once you have the engine located in the engine bay. There's a few companies that advertise in the different mags here in the UK that make custom headers to order. I'm sure someone here or one of the vendors can supply the length and diameter of primary you should be looking at. And many exhaust companies sell collectors as well.

While I'm on the subject of exhaust if you plan on duals then 2.5" diameter should be fine, although 3" duals would probably show better PEAK numbers if you plan on the full h/c setup with a big cam. A Y pipe setup must be a minimum of 3" diameter but 3.5 or 4" would be better for flow. Also ensure the silencers/mufflers you get flow sufficent for the HP. It's amazing how many don't. I can supply more info on this if you want.

All this won't be cheap. If you wanted more of a budget build.

-01+ Ls1 5.7 this means latter heads and Ls6 intake plus the factory exhaust manifolds are slightly better the previous years.

-Port the TB (see sig)

-Add a Cold Air Intake (CAI) and free flow filter

-Thunder Racing Trex cam

-Tune

It wouldn't be ideal and the exhaust would be restricing the cam but it should still make some impressive numbers. Several cam only Fbody's with the Trex have made upwards of 420rwhp in the past.

Sorry for so long, but as you can tell there's a fair amount of info