LS1 Throttle Body on 304

[GunnVK]

Hi guys,
I heard you can fit an LS1 throttle body onto a 304. Is this a fairly straight forward swap? Will I need the LS1 MAF meter to go with it?

Thanks!

[HoZy]

It is not a "bolt on" job.

Cheers
Mat

[GunnVK]

Would you care to explain how hard it is to put on?

[cander24]

The throttle body mounting stud arrangement is totally different between the two. Also the 5litre tb has 2 studs whereas the ls1 has 4. You're going to need to make up an adaptor plate that suits the ls1 tb mating face on one side, and the 5litre manifold on the other. This adaptor plate would also have to be internally tapered to suit the bore size of tb down to the inlet manifold, otherwise your inlet air charge will be like hitting a wall ubstruction. Better though would be to enlarge and port manifold to suit but this would require its removal. You may also need to customise the throttle cable holder and linkage on the ls1 tb.
No you wont need to use the ls1 maf sensor. You can, but its not necessary. This is because any increase in inlet air charge flow you may gain will still be within the scale of the stock 5litre maf.

[wraith]

Why would you bother any way.

[Munz]

Also the 5litre tb has 2 studs whereas the ls1 has 4.

LS1 is 3 bolt
LS2onwards 4 bolt

See Mace about there 70mm throttle for V8

[GunnVK]

Thanks for the help. I was just told it was possible to run then but didn't realise how much work is involved. Would the gains be worth the effort of making it fit?

[Grennan]

Thanks for the help. I was just told it was possible to run then but didn't realise how much work is involved. Would the gains be worth the effort of making it fit?

Youre better off looking for a ported 304 TB if you are looking at changing it. However, gains are usually pretty small. You are going to be bottle necked somewhere, changing the TB moves the bottleneck down the line. I know on the LS1 changing the TB is usually a waste unless you change the manifold because that diameter remains the same. Im not sure how it works on the 304, but I would imagine its very similar.

[VQ-Assault]

It may make some difference but due to the low 500cfm ish nature of the stock manifold it won't do much. Even with the Mace throttle body kits out there and their reconfigured stock manifold they're not worth it either. A Harrop dual plane with a decent 1000cfm throttle body on should do fine- bit more stuffing around but

[GunnVK]

Ok thanks for the help and info! I might just give the stock one a tidy up till I can get enough $$$ for a decent one.

[Reaper]

Youre better off looking for a ported 304 TB if you are looking at changing it. However, gains are usually pretty small. You are going to be bottle necked somewhere, changing the TB moves the bottleneck down the line. I know on the LS1 changing the TB is usually a waste unless you change the manifold because that diameter remains the same. Im not sure how it works on the 304, but I would imagine its very similar.

^^^^^ that. Changing the TB on a holden 5 litre is a waste of money unless you do the manifold to suit. If you want to do that you really need more compression/revs and a engine rebuild would be in order.

Reaper

[Munz]

It may make some difference but due to the low 500cfm ish nature of the stock manifold it won't do much. Even with the Mace throttle body kits out there and their reconfigured stock manifold they're not worth it either. A Harrop dual plane with a decent 1000cfm throttle body on should do fine- bit more stuffing around but

The intake manifold only flows as much as the throttlebody. Peter starr found this out when develping the starr manifold....the standard 65mm throttle flows 550cfm but when replaced with a 90mm it flowed 1200cfm

Abraisive flow engineering in sydney can make your intake flow better with the standard throttle
and even flows better with a larger one
Taken from another forum

STOCK V8 HOLDEN EFI INTAKE MANIFOLD.
Flow Tested with stock 65mmT/Body bolted on & wide open.
Runner no.
1.--------211.3
2.--------213.8
3.--------209.3
4.--------203.8
5.--------205.3
6.--------202.7
7.--------201.9
8.--------206.2

STARR CONVERTED HOLDEN INTAKE MANIFOLD had been PORT MATCHED
Flow Tested with Starr 90mm T/Body bolted on & wide open.
Runner no.
1.--------237.8
2.--------231.3
3.--------233.1
4.--------236.4
5.--------234.8
6.--------230.1
7.--------235.3
8.--------231.8

OUR EXTRUDE HONED STOCK HOLDEN INTAKE MANFOLD has been PORT MATCHED
Flow Tested with the stock 65mm T/Body bolted on & wide open.
These numbers would be higher with a 68mm or 70mm T/Body upgrade, we did not have any other upgraded T/Bs at time of testing.
Runner no.
1.--------248.6
2.--------245.9
3.--------245.7
4.--------247.3
5.--------240.1
6.--------249.3
7.--------246.7
8.--------249.8


This is the above same intake manifold but a Starr 90mm neck & T/Body has been tig welded on.
Flow tested exactly the same way as the above manifolds.
Runner no.
1.--------268.3
2.--------266.9
3.--------266.8
4.--------272.1
5.--------269.2
6.--------270.8
7.--------266.3
8.--------268.7

Surprising what you can get out of a bunch of bananas.

[GunnVK]

That's interesting. Thanks for that.

[immortality]

There is some gain to be had by bolting on a larger TB but the neck on the manifold is about 68mm to putting on a TB larger then that is a waste of time unless you modify the manifold first. No point putting on anything more then a 70mm TB.

considering the price of the star manifold money can be spent more wisely

cheers

[MACE]

The throat (neck) diameter of the EFI 5L manifolds we have here vary between 69-69.5mm

For people who are considering porting their EFI 5L manifolds and are planning on getting a custom tune done, we'll have in stock LS1 throttle body adapters to suit. The price for the adapter kit will be around the $130 mark. All that will be needed in addition to the kit will be a modded throttle linkage or LS1 throttle a cable.

It's no Group A setup, but then again some people options, who can't afford one for arguments sake

[Munz]

steve,

For the OP's sake do you know how much the intake neck can be ported?

ie. can it be matched at 75mm same size as the LS1 throttle?

[MACE]

steve,

For the OP's sake do you know how much the intake neck can be ported?

ie. can it be matched at 75mm same size as the LS1 throttle?

Good question. I dare say to get the neck of the manifold ported and the runner match ported/cleaned up would be around the $300-$400 mark give or take. You would be able to port the neck out 75mm to suit a stand bored out LS1 throttle body. I say bored out as the minimum throat diameter on a LS1 throttle body is 72mm (the butterfly though is 75mm)

[stuntmanmike]

OUR EXTRUDE HONED STOCK HOLDEN INTAKE MANFOLD has been PORT MATCHED
Flow Tested with the stock 65mm T/Body bolted on & wide open.
These numbers would be higher with a 68mm or 70mm T/Body upgrade, we did not have any other upgraded T/Bs at time of testing.

Awesome info. I wasn't aware that the extrude hone process could be as effective. If the flow data figures are correct then I am keen to give this a go myself.
I'd rather have the low profile manifold than the TB/Air-filter assembly peeking through the bonnet and attracting the wrong attention. The missus prefers the way it "used to look" over the bonnet without the engine inspection hole that was cut and so I reinstalled the stock manifold setup and the stockie bonnet.

I'd really like to know if there is a sure way to insulate the heat transfer from the block to the inlet manifold. I've had to place a towel over the bunch'o'bananas to keep myself from getting 2nd degree burns when working on the engine and it seems to take bluddy ages for the manifold to cool down when it is parked (the local feline vagrants use that as a heater blanket a night. Argghh!).

I apologise for the additional comments regarding heat transfer if this has been addressed elsewhere and is not considered as part of this thread. Cheers all!

[Reaper]

............nm

Reaper

[kuzman89]

don't bother with V8's, get a V12 TT