forrestd

If you were to build a street car, to be used for occassional "casual" circuit racing, would you go with the 402 or 427? The car in question is an '04 Holden Monaro (it came with LS1 from the factory but currently has heads/cam).

What characteristics between 402 and 427 do you think would be suited (or not) to circuit racing? Maybe there is something in between 402 I should be considering as well.

Would the application of revs/power be much the same with these two motors (just bigger power with bigger cubes?) or would I be sacraficing something with the larger motor i should know about? Same goes for street drivability I guess... would the 427 = just bigger grin factor? or do I sacrafice something i may wish to retain with the smaller motor (apart from fuel economy).

KHShapiro

iTrader: (10)

check out my link on my engine in my sig.
402 is cheaper but 427 has a bit of bragging rights

gnx7

iTrader: (28)

If you have the $$ build a dry sump factory LS7. The LS7 intake flows the most out of any production/FAST intake and supports higher RPM breathing with large factory 2.2" lightweight titanium valves in the heads. They help these small block heads flow like big block style heads plus the port design is awesome for all around flow/velocity. Also with dry sump oiling you will have no oil control problems which F-bodies and even Vettes sometimes suffer from on the road course (ie fried bearings)

rjkZ28

can you run a wet sump with an ls7 top end?

Ryne @ CMS

iTrader: (10)

yes you can

SLED28

iTrader: (7)

Sometimes the smaller motor is better b/c its easier to hook out of the corners, it'll charge good topend, but will have a little less mph in the straights then the bigger cube 427.

forrestd

thanks for the comments; it sounds like the 402 might be the way to go, with the 427 yielding only slightly more on the straights, yet costing significantly more. What sort of power are the 402's making in the states?

02ZOh6

500-550rwhp ballpark

forrestd

Been a while but here's an update. We ended up putting together a 438ci motor (using LS7 block) with L92 heads and L76 intake. I was initially worried if would be "lazy" and not spin up as quick as my 346, or even a 402.

How wrong was I? The thing revs up QUICKER than my old head and cam 346 LS1. It dyno'd at about 505rwhp, however i believe aussie dynos may read lower than US ones (if that matters, doubt it).

At the srtrip we've run 11.0@125mph on 15" ET Street radials; it should be good for a 10 i suppose.

Here is some video of some circuit / road course action from yesterday:

http://www.youtube.com/watch?v=R4NXBTIbVpk

slow trap

iTrader: (22)

if you get tired of your current power level change out the top end over to the ls7 heads/intake and you will pick up an easy 50 rw.

KHShapiro

iTrader: (10)

how did you come up with that displacement number?

jermzz

iTrader: (18)

4.1 stroke x 4.125 bore.

95FbFormula

iTrader: (25)

For the track racing side of it I would go with the ls7 is weights almost the same as the ls2 but is designed for road coarse.

forrestd

Funny you should mention that, i've ordered a set of LS7 heads from Texas Speed, however they seem to have trouble devilering the product for some reason.

jermzz

iTrader: (18)

WHY do I keep hearing negative things about TSP lately? I got a quote from them not to long ago, but lately i've really been considering going a different route with a builder.

forrestd

Yep we did (go with the LS7)!

RoysTransAm

Nice vid.... how you guys shift with your left hand I'll never understand.

Speedpup

If money is no object do a 427. If money is a consideration and you are going to track the car do a 402 and with the money left do suspension and brakes. HP is not everything on a road course.

forrestd

Sorry i was kind of digging up an old thread.

We ended up doing an LS7 438ci motor, which is the car in the video.

SS Enforcer

Actually we Aussies wonder how you guys manage it with your right hand whilst steering with the left. I have driven RHD stick shifts and it's a real pain I seem to lose the timing between the clutch and hand. But I never got the hang of leaning my right arm on the door.

cheers