Hi-comp 18RG cam selection help

**Celica RA45** · 14-11-2005, 07:43 PM

tricky the weak link in 18rg s are the rod bolts and rods if you can afford some forged 1s better if not put chevy big block rod bolts into your rods they are the arp spec and will go in and no more spun big ends

**tricky** · 15-11-2005, 11:14 AM

Yeah, I've been researching big end studs for a while now. They definitely seen to be the go for an engine which could spend some time around 9000rpm. Is there much machining to get the chev studs in? I'm not sure whether I'll get forged rods. Ideally, I'd like to, but I don't know ehther I could justify the cost. I might just get the original rods shotpeened and keep my fingers crossed... I'm also worried about weight. I'd like to keep the mass of the reciprocating parts low-ish. What is the mass of forged rods compared to the stock rods? My guess would be a fair bit heavier...

**Celica RA45** · 15-11-2005, 03:49 PM

the forged rods will be lighter and stronger also 18rg are known to oil surge so make sure you either baffle the shit out of the sump or put in a accumalator which they used in the group C days which works as when the oil presssure drops it shoots 2liters of oil into your main gallery so you dont spin the big ends

**tricky** · 15-11-2005, 05:04 PM

Sump wise, I was thinking of making an alloy sump. For the oil pump, I guess TRD ones are a thing of the past. Would there be any need to change to a higher capacity unit, or would a tight stock 18RG one be fine? oiling is one of my concerns for this buildup, but I don't want to go to the effort and expense of a dry sump on a vehicle that will be predominantly street driven.

BTW, thanks for all the real world advise, Celica RA45!

**Mr DOHC** · 15-11-2005, 05:40 PM

they make ARP rod studs for 22R, which also fit 18R, just get them

**Steve M** · 20-11-2005, 07:24 PM

Damo, I just wanted to shed a little light on the Toysport pistons for you.

They are based on the 9.7:1 stock pistons except for these features: (and possibly others)
92mm bore, as you already know
1.5mm deeper valve reliefs
2mm wider valve reliefs

They are made for toysport by Venolia.

**Damo82** · 21-11-2005, 05:31 PM

Steve, thanks for that. Considering they are based on the 9.7's and have wider and deeper reliefs that eases my concern a bit regarding valve interference. Being 92mm bore that will hopefully give me a bit more grunt down low but I don't want to lose that with the wrong cams.

**Sam_Q** · 21-11-2005, 06:30 PM

by going out to 92mm what does that take the displacement out to?

**tricky** · 21-11-2005, 09:25 PM

See earlier post. 2148cc.

**andrewvibert** · 24-11-2005, 10:21 AM

Do yourselfr a big favour and stick with the Trd grind cams. 304 and 288(rally spec). If you want more go 304/304(race spec) . I have tried many cams over the years and nothing comes close to these cams.