23 replies to this topic

[Muncher]

As some of you may know I'm about to DIY fit a supercharger kit to stage 1 power levels, then soon after fit a chargecooler and smaller pulley to take it to ~255bhp. However, I'm been looking into building another engine which would handle 300bhp and more, despite getting some great prices for things the cost of this, is well, a lot! What I would like to know is whether those of you that own a supercharged car think this is adequate for what you use the car for? I'm beginning to wonder if going past stage 2 is worth the expense as at that point you have to start looking at the internals and once you start there it doesn't make any sense to do a less than proper job. The numbers I'm looking at appear to be stunning value compared to the cost of something like a supercharged Honda conversion for an Elise. They're affordable but I'm unsure whether I'd rather have the money for a house deposit for when the market really is at rock bottom... It will mainly be used as a road car, but I keep meaning to get it on track more often. If its outright laptimes I'm looking for I think driver training would be more useful.

[cheeky_chops]

As some of you may know I'm about to DIY fit a supercharger kit to stage 1 power levels, then soon after fit a chargecooler and smaller pulley to take it to ~255bhp.

However, I'm been looking into building another engine which would handle 300bhp and more, despite getting some great prices for things the cost of this, is well, a lot!

What I would like to know is whether those of you that own a supercharged car think this is adequate for what you use the car for? I'm beginning to wonder if going past stage 2 is worth the expense as at that point you have to start looking at the internals and once you start there it doesn't make any sense to do a less than proper job.

I think everyone has that question whether its NA, T or SC - diminishing returns on cash spent and is it any "better"? Well define better....?

I havent actually spent that much on my VXR to give 290lb/ft - zorst, remap, injectors, clutch, fly = £3k. The next step is chargecooler +rad which is £2k. Add to that service, cambelt, ohlins rebuild, couple of other bits and i am looking at another £3k for 30bhp/30lbft. Hmmm. I could knock £1k off and go for a larger IC but i still havent seen any results (either way) from it

Personally, i like the double take bikers have when i am very large in their mirrors!! Decisions, decisions....

[vocky]

my advice would be to stick with 250 bhp, it's cheap (ish), it works you are in the same position as me, my phase 2 build will cost about £3k, £2k is just for the cylinder head stuff I do sometimes ask myself why I bother when my vx goes so well already it gets scary when you want to pass certain bhp levels

[VIX]

I think that unless you're a real track fiend it is difficult to justify anything but the most basic of mods (brake pads, geo and a remap to get rid of the flat spot). Anything more than that can only be on the basis that it's there, you want it and you can afford it. IMHO of course.

[MAXR]

It's a dilema I'm faced with...More power? you can never have too much? Well, my car is now at 260(ish) and that's enough for me for track use so long as I can shed a little more weight. I have uploaded a video clip in the thread on Bell & Colvill @ Snetterton, take a look, 260bhp is just enough, save your money, keep a reliable engine & enjoy driving!!! I used 146 ltrs of fuel that day & drove for over 4.5 hours, like I do most track days...The engine is strong & sorted. I will be up loading another clip later...

[Muncher]

To put it into perspective the new engine would cost me £3k in a fully machined, balanced (entire engine) and built for me state. That's including clutch, flywheel, balancer shafts gone and all the internals good for significantly over 300bhp. Best guess would be I could get that down to a hopeful £2.5-£2.7k. Then I'd need to sell my engine, not sure how much that would raise with 52k, piper cams and revised chain kit...

[NickB787]

Muncher I can finally say I will let you know in a few weeks. You will know I have been waiting for certain parts to arrive. It WILL be here this week. The setup will be similar to the one you are after. I think 300bhp will be the mark. I am using an almost standard engine. I will change the rods, BS delete, comp blower cams, ported head. arp studs, pro alloy charge cooler,3 in 2tublar, and a harrop TVS. I hope i won't be disapointed and it will still be by daily drive. I do wonder though if 260 ish is about right, max's car with his setup for the track is seriously fast....

[MAXR]

Muncher I can finally say I will let you know in a few weeks. You will know I have been waiting for certain parts to arrive. It WILL be here this week. The setup will be similar to the one you are after.

I think 300bhp will be the mark.

I am using an almost standard engine.

I will change the rods, BS delete, comp blower cams, ported head. arp studs, pro alloy charge cooler,3 in 2tublar, and a harrop TVS.

I hope i won't be disapointed and it will still be by daily drive.

I do wonder though if 260 ish is about right, max's car with his setup for the track is seriously fast....

Nick,

Your car WILL be super fast....Maybe I will wait to see how the reliability holds up first. After speaking with many of the race car owners over the past few months, many regret pushing just that little too far. Mind you, a 300bhp S/C Vauxhall engine may prove ultra reliable too. Like your car, my engine & supercharger has never missed a beat since it was installed...

...Will the oil pump need upgrading?

[Winstar]

...Will the oil pump need upgrading?

the Oil pump should be fine unless your going for 7500+ rev limit and spending alot of time there, it was designed with alot of spare capacity the same one in the SAAB engine also runs Piston cooling oil jets and a Turbo.

[Muncher]

Nick, GM rate the pistons at only 250bhp according to edition 3 of the build book... ARP head bolts are overkill as well apparently. I'll be very interested in seeing what you get, only yesterday was I asking Jon whether you'd be interested in giving up your Harrop

[NickB787]

Nick, GM rate the pistons at only 250bhp according to edition 3 of the build book...

ARP head bolts are overkill as well apparently.

I'll be very interested in seeing what you get, only yesterday was I asking Jon whether you'd be interested in giving up your Harrop

I wondered about the pistons both the guys in the State I spoke to and here / Germany recon I should be ok upto 300bhp , Wonder why the gm book said that?

I did think about the pistons at one stage but that mould mean a complete strip and rehone out of the car, at least this way I can put the rods in situ. I wont be going over 7500rpm I was thinking of limiting it to 7000-7200.


Max, oil pump should be ok but I may need a larger/second fuel pump.

[MAXR]

Nick, GM rate the pistons at only 250bhp according to edition 3 of the build book...

ARP head bolts are overkill as well apparently.

I'll be very interested in seeing what you get, only yesterday was I asking Jon whether you'd be interested in giving up your Harrop

I wondered about the pistons both the guys in the State I spoke to and here / Germany recon I should be ok upto 300bhp , Wonder why the gm book said that?

I did think about the pistons at one stage but that mould mean a complete strip and rehone out of the car, at least this way I can put the rods in situ. I wont be going over 7500rpm I was thinking of limiting it to 7000-7200.


Max, oil pump should be ok but I may need a larger/second fuel pump.

I assume you will be upgrading your clutch at the same time...When Back on Track swapped gearboxes for me they found that the Courtenay Fast Road clutch springs were a little slack and so I upgraded to the Courtenay race spec one...It sounds like several of you are hell bent on pushing the S/C limits even further, I just hope you don't get heating problems and that you also upgrade your brakes and driving skills to match. as there's been enough lost cars of late

My car revs to 6950 and sits up there happily for much of the time on standard Rods....If I could do anything to improve the engine, it would be to increase the rev limit to 7500 or 8000. I'm sure the 2ubular manifold & exhaust will unleash some extra top end grunt.

I'm looking forward to seeing your Dyno Graphs after the conversion!!!!

Max

[PaulCP]

It's a dilema I'm faced with...More power? you can never have too much? Well, my car is now at 260(ish) and that's enough for me for track use so long as I can shed a little more weight. I have uploaded a video clip in the thread on Bell & Colvill @ Snetterton, take a look, 260bhp is just enough, save your money, keep a reliable engine & enjoy driving!!! I used 146 ltrs of fuel that day & drove for over 4.5 hours, like I do most track days...The engine is strong & sorted.

I agree

Whilst yours pushes out more than mine Max the one thing i can vouch for after 3 years of SC driving (mainly track use with the odd long Euro trip) is the reliability (car is still on the original clutch after 7 years). I would be wary of heat build up in the engine bay & around the exhaust when going much further. Had to ditch my Jimsan diffuser for that very reason.

Also if i was using the car mainly on the road the current power levels are more than adequate 99% of the time.

Edited by PaulCP, 17 September 2008 - 08:42 PM.

[Muncher]

They may well be OK, but it seems GM have rated them to the same power levels as the rods which are most definitely a concern. There would always be a concern in the back of my mind that you were pushing them too hard... Replacing them changes the costs and scope of things hugely, but it's a risk without it. Are you happy to accept the engine may grenade itself at some point and you would be happy to rebuild again? I can't see a tuner agreeing they'll rebuild the engine for you if the pistons fail past their know limits. The more I read the more sense it makes to stick with 255bhp and see what happens with you Nick

[NickB787]

They may well be OK, but it seems GM have rated them to the same power levels as the rods which are most definitely a concern. There would always be a concern in the back of my mind that you were pushing them too hard...

Replacing them changes the costs and scope of things hugely, but it's a risk without it. Are you happy to accept the engine may grenade itself at some point and you would be happy to rebuild again? I can't see a tuner agreeing they'll rebuild the engine for you if the pistons fail past their know limits.

The more I read the more sense it makes to stick with 255bhp and see what happens with you Nick

Thank you so much

[Muncher]

Better I told you now I guess If I thought I could get 300bhp by only really changing the rods, supercharger and exhaust I'd do it in a shot

[VX AZ]

Better I told you now I guess If I thought I could get 300bhp by only really changing the rods, supercharger and exhaust I'd do it in a shot

So is around 250BHP the max you can get with a standard engine and a supercharger? I'm doin mine in May next year!!

[MAXR]

Better I told you now I guess If I thought I could get 300bhp by only really changing the rods, supercharger and exhaust I'd do it in a shot

So is around 250BHP the max you can get with a standard engine and a supercharger? I'm doin mine in May next year!!

You can get to around 270bhp (ish) if you have a 2ubular with standard engine.

[VX AZ]

Better I told you now I guess If I thought I could get 300bhp by only really changing the rods, supercharger and exhaust I'd do it in a shot

So is around 250BHP the max you can get with a standard engine and a supercharger? I'm doin mine in May next year!!

You can get to around 270bhp (ish) if you have a 2ubular with standard engine.

Jesus!! So I would need to change my Larini then?!

[VIX]

So is around 250BHP the max you can get with a standard engine and a supercharger? I'm doin mine in May next year!!

That is the perceived wisdom. Don't know that anyone on here has risked going higher. Perhaps some of the Euro-Speedy owners?