Original cylinder rebored to 175 vs Rayspeed alloy 175 kit?

[Nerdy Norm]

It's a long story, but I've got the choice of fitting one of these to my cheapo S2 LI rustoration:

Option 1: the original 150 barrel, bored to 175cc by AF Rayspeed, with a matching Mahle piston and SIL 175 head. No porting work done.

Option 2: AF Rayspeed-fettled alloy 175 kit (stamped AFR, so presumably better than an Ebay special). Exhaust and inlet ports matched to manifolds.

I'll be using it with a Scootopia SH2/22 and an AFR 42mm Clubman.

My head is saying go for the original iron cylinder (newly rebored to 175), but my heart is tempted by the port-matched alloy kit. Should I be concerned that the alloy kit already has helicoil inserts for the exhaust studs, straight from Rayspeed?!

Eventually, I'm sure that I'll be upgrading to a "premium" kit (probably the same BGM RT195 I'm already running on my S3), but for now one of the above is my only option.

Any help in making my choice would be much appreciated!

[Tractorman]

Why not leave it 150 until you do you preferred upgrade.

[barnsleybilly]

If your saying you'll end up with a premium small block kit and thats where you want to be, then don't waste your money on an interim solution. Put some money aside every month + add the cost of the AF kit/ rebore will get you where you really want to be sooner.

[EddieStone]

If it's a stop gap measure to get on the road while you save up for the GT, I'd fit the bored out original barrel. It'll definitely fit, and will definitely be easier to set up. You could cut a couple of mm off the piston skirt to increase the port timings slightly if you wanted a slight improvement.

[Nerdy Norm]

Thanks guys. Money's not the question here, I have both options sitting in the garage ready to fit (whatever I don't use can go on eBay). So it's really about which one will give better performance. And I don't have the option of leaving it at 150 as the original barrel has already been bored to 175.

[Daggs]

May I suggest the kit you don't use is offered on here rather than eBay.

[EddieStone]

In answer to your question, the one with the matched manifolds will probably go better, but I would check the port timings. Measure them and see if they are the same.

[stew]

Why not get your iron barrel bored out to 175 and get the ports fettled?

[Nerdy Norm]

Good idea, I'll put the unused kit it on here

Basically, I want to fit whichever top end I decide on this evening. Rayspeed (who rebored the iron barrel to 175cc) told me that to have it ported would take 2 or 3 months (versus a week for just the rebore), so that wasn't an option. I don't have the technical ability to check port timings etc., so I'm inclined just to go with the rebored original iron barrel, as hopefully it'll be easier to set up than the Rayspeed alloy kit.

[EddieStone]

Just measure up from the base and compare the distance to the bottom and top of the inlet and exhaust port. See if they are the same. You can visually check the small transfer ports and see if they are similar sizes. If any of the port holes are bigger, then it is likely to go faster. Or at least, use more fuel!

Are you using the same head on each?