LS3 top end swap

[mikeyb1987]

Hi everyone,

For those of you not following the HSV Holden UK Facebook page, I thought I'd share my build on here. It's a popular modification over the pond, but only one other person (that I know of) has done it over here- that being GelfVXR.
From what I've read, heads quickly become a bottleneck when tuning- for my intended power goal, upgrading to LS3 heads appears to solve this. So, the power goal.....I want 400rwhp, and 300bhp/tonne.
The heads I acquired are from SDPC, from the US. They have been CNC'd, so hopefully should help in my power goals.

[mikeyb1987]

A picture of the heads is here:

[mikeyb1987]

SturdyHSV said:

We have the same goals

You can't beat nice round figures as goals

[mikeyb1987]

On top of the above, the other parts ordered were:
-Brian Tooley .0660 dual springs with titanium retainers
-Brian Tooley trunnion upgrade kit
-Brian Tooley lifters
-LS3 injectors (I also bought a set of LS9 injectors, before realising they were sub-optimal, due to spray angle)
-Oil pump: standard GM pump, as there was no need to go aftermarket.
-timing chain: again, standard, as no need to go dual.
-timing cover
-offset intake rockers (due to them being LS3 heads)
-LS3 head gaskets
-other bits and pieces

[mikeyb1987]

Unfortunately, the heads were actually L92, not LS3. The key difference being the valves- the LS3 valves are considerably lighter than L92 ones. Therefore, in addition to the above list, I ordered LS3 intake and exhaust valves.

Sorry about all the posts guys the forum software doesn't like long posts from mobile devices!!

[mikeyb1987]

jameshsv said:

Nice shiney heads I like very much.How much wer the heads

They were circa £1,400, including the intake.

[mikeyb1987]

007 VXR said:

Good luck

Cheers

[mikeyb1987]

jonnM said:

You need to get that OCD looked at

I take it you saw the pic on FB last night?!

Edited by mikeyb1987 on Saturday 8th March 20:04

[mikeyb1987]

James has beaten me to my next post- cams!!
I have never vacillated over anything as much as cam choice. At this point, I will state that if you do not have the time (or want to spend the time) looking for a cam, then an off-the-shelf package is probably a good idea for you. I spent 12 months on and off researching US/Aus forums for a cam which would provide be power, but be suitable for a daily driver. Towards the end, after seeing emission results for large-ish cams, I decided on going for a pretty big cam.
So, the spec.....I'm not one to hide specs. It is a 22*/23* 0.610/0.617 with an average LSA.

[mikeyb1987]

SturdyHSV said:

Yeah, 500bhp fly seems a good number, and would like weight down to 1600kg for nice 300bhp/ton.

Cam needed for noise though, so round figures may go out the window

I have to admit to getting a bit giddy about hearing it idle for the first time

[mikeyb1987]

So, being an accountant, I wanted to bring some numbers to the show. To ensure I can reasonably estimate the power increase, I needed a 'before' dyno run, preferably on the dyno it is going to be mapped on. This meant a trip to Doncaster on Friday for a quick power run:

[mikeyb1987]

The figures were 322rwhp and 397 at the fly. The torque curve certainly differentiates from the usual euro-box hatches on the roads

[mikeyb1987]

A few people have said that rolling road under-reads, but it's not an argument I'm going to get into, although I am inclined to agree.
For reference, the car already has headers, sport cats, cat-back and OTR intake. It certainly seems to perform well at Thunder Road and 1/4 miles, and crucially on the road too.
As I mentioned in the above post, the actual figures are nonsense until the car is finished.

[mikeyb1987]

ringram said:

That should do more than 400rw imo.
Cam spec isn't huge if they are at the low end.

Who is tuning?

John Sleath is doing the tuning.

[mikeyb1987]

Thanks Gareth! The cam is a custom Comp Cams LSR 223/231 114. With regards to the stock injectors, I had to switch to an LS3 style. Apparently the fuel rail (although the same part no.) sits lower on LS3 engines, so LS2 injectors would not fit.

[mikeyb1987]

Quick update:

Just rang Stuart at AAS and the cam is in and front end re-assembled. Just one query with the spring installation, and (hopefully!) it will be good to go. CAN. NOT. WAIT.

As ever, Stuart is working like a trooper, so a nice bottle of single malt may make it's way to him

[mikeyb1987]

Monaro5.7 said:

Ahhh some one following my lead

As i said at the meet mate look forward to ur result. Your real tatget is 420rwhp as i have 419rwhp but iam sure you will beat that with the better heads and head internals

Have you got LS3 heads too??

As it's an unknown (due to Gelf being the only one previous to me who has this setup), I'm trying not to get my hopes up. 420+ rwhp would be magic

[mikeyb1987]

EssexVXR8 said:

Derr! Don't understand the extra cubes bit as swept volume has not changed, larger combustion chamber will give it a lower compression ratio. so this will loose power unless skimmed to reduce

The heads have been skinned by (I think) 0.030" to maintain standard compression.

[mikeyb1987]

mfp4073 said:

I thought I knew about cars...having read this post a couple of times I now know I'm thick!!!!
thanks for boosting my automotive confidence.

regards John

I know what you mean!
My thread may have been slightly hijacked, but it's great to see some technical info on the forum

[mikeyb1987]

Quick update:
The cam/heads have been installed in the car and it was dropped off for mapping yesterday.
I have to confess to letting out a small giggle when I fired it up! The idle was a tad low, but it did give it some proper lope. It also rocked the car on idle a hell of a lot more than standard! Unfortunately, I fear the mapping will 'tidy up' the idle.
I eagerly await the results