20 replies to this topic

[Gump]

hi all

i was talking to a mate at work last night, he has a hq 4 door gts, he was saying that he was looking into putting a 333 stroker into the old girl. i suggested a 355 stroker.

so i was wondering if i could get some info about what needs to be done to a blue block to fit one of these strokers? pretty sure you need the bottom of the bores machined for clearnce??

also he wanted to know a rough sorta price to aim for?, and brands i told him not to go for and he agreed about not getting a stroker kit thats been welded up

gump

[antelopeslr5000]

Some of the 5 litre Holden blocks are cast with the bore relieved for a 5.7 litre (355ci) stoker engine so no grinding is neccessary unless you want to go bigger in capacity

When HSV introduce the Holden 5.7 litre (using the Harrop crank) all Holden V8 5 litre blocks from then on were cast for use for a 5.7 litre crank regardless whether they were used for a 5 litre or 5.7 litre engine.

Edited by antelopeslr5000, 17 January 2007 - 08:01 AM.

[Gump]

okay cheers for that guys. i think he might want to keep his standard heads (think they have had work done). he has the blue commonwhore block so he will need to do a bit of machine work to the block.

yeah been thinking with my hatch if things are what ive been told inside the block a 355 would be a fun option be easyer to hit the 350 flywheel horse out put

[lakeside]

Some of the 5 litre Holden blocks are cast with the bore relieved for a 5.7 litre (355ci) stoker engine so no grinding is neccessary unless you want to go bigger in capacity

what about the blue 355 strokers in the VH's?

[ls2lxhatch]

Why would you spend $8-12K on a stroked holden V8 when you can buy a SBC or BBC for the HQ?

Edited by AndyCullen, 18 January 2007 - 01:31 AM.

[Gump]

he wants to keep it fairly orignal. or as orginal as possible

[Struggler]

A 355 with HQ heads is a real torquer, but unless the heads have been seriously dug out it will nose over early.

I personally love 326/330 type strokers with HQ heads.

If he really wants a 355 get him into some -3 Bennett alloys !!!!

[Gump]

struggler why do you prefer the hq heads over say vn heads on a small stroker. ive got one in the shed and just interested in you opiniion

[Struggler]

In most applications I still prefer the HQ head. The 330 CI engine size just suits them perfectly.

It all comes down to air speed. For an engine to be responsive and make good torque it has to fill the cylinders quickly and efficiently. Heads and manifolds with small port volumes achieve this. However it becomes a juggling act as a small port and intake can become restrictive at high RPM when they must move a lot of air quickly.

VN heads have a port volume about 60% larger than HQ heads. Combine this with a typical intake designed for VN heads and the volume of air the whole thing contains is about double that of HQ heads and a Torquer intake. To make this work we have to speed up the air, by more cubic inches or more RPM. This is why VN heads and Harrop single planes on 355's run so well. Stoke stroke VN headed Harrop manifolded engines need to rev to perform. It is not uncommon to have to use 5500-6500 rpm stall converters to get the best out of them. Stock stroke HQ headed engines with similar camshafts can get away with 3500 stall and be really snappy on the street. Consider also the VN combustion chamber is considerably larger than the HQ, adversely affecting your compression ratio (this is actually a benefit on large stroker engines.).

The best example of this is Larry Perkins Bathurst winning 304 back in the '90s. Everyone whinged about how Larry's engine was heaps faster up the hill and he must have been cheating. When the powers that be pulled his engine down all they found were intake port fillers, designed to reduce the intake port volume in order to increase air speed and therefore torque. This is why his car was faster up the hill, but the same as everyone elses coming down. Remember too that this engine was designed to change gears at 7500rpm! Another example is the popularity of Ford 4V intake tongues, a similar deal where small tongue shaped pieces of cast aluminium are bolted into the intake runner (I have some of these here at the moment and can post a pic if anyone is interested).

So to answer your question, a VN headed mini stroker will not be as good a street engine as an HQ headed one. It will however make more HP, but at a higher RPM. The HQ heads will make more torque in the RPM area you wil spend most time in. I have seen heaps of people spend good money putting VN heads on their stock stroke 308's only to pick up nothing at the strip, sometimes they even slow down !! They do eventually go quicker, but only after everything else is changed to suit the higher operating RPM of the motor (stall conv. diff gears etc).

Having said that, a 355 or 383 VN headed engine is a great motor for street/strip and competition use.

Its all horses for courses, you need to get the combo right for your application.

I hope this helped.

[Gump]

thnaks struggler i like reading your post very indepth and you write them well enough that i can understand them, not to many big scary words.

[dattoman]

So Tinks 331 should go OK

And I should consider this 325 bottom end my mate has sitting there for sale

[Gump]

if i get around to buying the vn heads of clint looks like i should go up to a 355 are there any diff's detween blue head and red/black heads?

[dattoman]

Are those heads ok ?
They were on the block they have now condemned and are looking for a new one

any head is good head

[Tiny]

Get back on the topic gents

Struggler: Thanks for the info mate! Your posts are always appreciated!

One thing that struggler mentioned that i think ALOT of people need to remeber...:

"Its all horses for courses, you need to get the combo right for your application."

Bigger is NOT always better, and You've gotto remeber your combination to get the most out of it!

Cheers.