Chimaera 450 SC Problem

[jojackson4]

Do the dump valve first
Then start at the beginning
If the dump valve is fubard you will be kicking your self

[BarnFind]

macdeb said:

It sounds good ?!

[450Nick]

BarnFind said:

dumping boost to atmosphere..doesn't that sound great !

Exactly, the Rotrex is capable of having the impeller spun faster than it's being driven by the recirculated air, so you get better pickup - by dumping it to air you just lose the benefit...

[KateV8]

Thread bump. Did the OP find a solution? Our car is currently having the SC Power kit so would be interesting to know if it was component failure.

[maxxander]

KateV8 said:

Thread bump. Did the OP find a solution? Our car is currently having the SC Power kit so would be interesting to know if it was component failure.

Sadly still a lot of head scratching going on and no conclusions as yet. At the weekend a gauge was rigged up to measure the pressure leaving the supercharger, it registered 25 PSI at 2500 RMP and is this is a new engine build we were reluctant to take the revs much above 3000RMP with no load. I can't believe these figures as other people have quoted between 6 and 10 PSI as the optimum boost, having said that the suppliers are being very helpful and we are working through possible scenarios. I must admit at this point I'm feeling very much out of my depth and have to rely on the expertise of others. Having now been without the car for 15 months, I wonder if I'm ever getting it back and can honestly say I wish I have never started the project. 16 months ago I had a car that ran beautifully and eighteen grand later I have a very pretty engine bay which at some undefined time in the future will hopefully run as it should.

[Richard 858]

You have my sympathies Max, although I took on this project myself, combined with full suspension refurb & rear brake upgrade (to compliment fronts done last year) I do know the feeling, and I now feel quite lucky having only been off the road for 5 months. I too had a 450 in good condition that ran well & gave good power for an unmodified example and I've been regularly reminded by SWMBO that " I thought you bought a car that didn't need anything doing to it !" but she has been extremely understanding.
Try and keep the faith as, whilst I still have some fine tuning to do, I'm sure once you get in the drivers seat again you'll very quickly get that massive grin back on your face, especially when you get that kick back in the seat when you floor it at 3,000 rpm & remember just in time to back off the throttle before, all of a sudden being at the next roundabout/junction/home !

[KateV8]

My sympathies too Max, hope you find the elusive culprit soon. Made me laugh when you mentioned your other half's comment, how often have I heard that over recent years? Keep the faith, it will be worth it in the end.

[450Nick]

maxxander said:

Sadly still a lot of head scratching going on and no conclusions as yet. At the weekend a gauge was rigged up to measure the pressure leaving the supercharger, it registered 25 PSI at 2500 RMP and is this is a new engine build we were reluctant to take the revs much above 3000RMP with no load. I can't believe these figures as other people have quoted between 6 and 10 PSI as the optimum boost, having said that the suppliers are being very helpful and we are working through possible scenarios. I must admit at this point I'm feeling very much out of my depth and have to rely on the expertise of others. Having now been without the car for 15 months, I wonder if I'm ever getting it back and can honestly say I wish I have never started the project. 16 months ago I had a car that ran beautifully and eighteen grand later I have a very pretty engine bay which at some undefined time in the future will hopefully run as it should.

Have you been testing it against a closed plug? Obviously when the engine is sucking air in and blowing it out the other side, the pressure is over and above the vacuum that the engine is creating. (So its boost, not pressure). You need to test what vacuum your engine is pulling at the same revs and subtract that from the SC pressure.

[maxxander]

Hi guys, thanks for all the support, I'll pass on your suggestions Nick450 but as mentioned previously I am now a little out of my depth. Just hoping now that I can get this all together in time to attend the Caring With Cars meet, I had intended this to be its first outing this year but that's now starting to look unlikely. As soon as I've got any updates I'll be sure to let you know. Thanks again, Tony.

[Hoofa]

Out of interest what size pulley are you running ?

[maxxander]

Hoofa said:

Out of interest what size pulley are you running ?

Hi Hoofa, just got the measurements off the builder, the supercharger is running an 85mm pulley as supplied by SC Power and the crank pulley is 175mm. Just as a matter of interest for those of you that are already running a supercharger, what spark plugs are you using? Mine kit was supplied with B7's. But I have been recommended to use B8's.

[450Nick]

maxxander said:

Hi Hoofa, just got the measurements off the builder, the supercharger is running an 85mm pulley as supplied by SC Power and the crank pulley is 175mm. Just as a matter of interest for those of you that are already running a supercharger, what spark plugs are you using? Mine kit was supplied with B7's. But I have been recommended to use B8's.

B7s are fine, 85mm pulley is the high boost pulley and should give you approx 10psi max boost with a rev limit on the charger of 6600rpm

[maxxander]

450Nick said:

B7s are fine, 85mm pulley is the high boost pulley and should give you approx 10psi max boost with a rev limit on the charger of 6600rpm

Thanks for that mate one more question, for the supercharger to run at 6600rmp to produce 10psi, what would the engine be revving at? Sorry, I feel like I am interrogating you, the advice is very much appreciated.

[maxxander]

450Nick said:

B7s are fine, 85mm pulley is the high boost pulley and should give you approx 10psi max boost with a rev limit on the charger of 6600rpm

Thanks for that mate one more question, for the supercharger to run at 6600rmp to produce 10psi, what would the engine be revving at? Sorry, I feel like I am interrogating you, the advice is very much appreciated.

[450Nick]

maxxander said:

Thanks for that mate one more question, for the supercharger to run at 6600rmp to produce 10psi, what would the engine be revving at? Sorry, I feel like I am interrogating you, the advice is very much appreciated.

Sorry what I mean is that the max rev limit of the charger is reached when the engine is at 6.6k revs. The charger rev limit is fixed. With a normal 90mm pulley you can run the engine up to 7.5k from memory (might be different). With an 85mm pulley you're spinning the charger faster so you hit the charger's rev limit when the engine is only at 6.6k. Hence if you go even smaller on the pulley then you will overspeed the charger at the engine's normal rev limit (hence why that is the smallest pulley size you can use here without dropping your rev limit).

No problem, information is meant to be shared!

[Richard 858]

I'm running a 90mm pulley as not worried about max. power yet as don't have the inclination to upgrade drivetrain yet.
But I am using B8 plugs, as recommended by Colin at SC Power, too early to tell (if ever) how much difference they make but I believe the main purpose is to reduce the risk of premature detonation.

[Hoofa]

Yep stick with the b8 plugs, to be safe side especially as your running the larger charger and therefore going to hopefully produce some good numbers. I tried b9 plugs on the advice of the engine builder but they just kept fouling , no probs with the b8 though


Also you might want to consider water injection, I have the larger intercooler, I was seeing some rather high intake temps last year even with the big intercooler. Once again the water injection is a insurance policy.

Edited by Hoofa on Friday 16th May 05:51

Edited by Hoofa on Friday 16th May 05:53

Edited by Hoofa on Friday 16th May 05:54

[450Nick]

Mr Supercharged said:

I'm in Gloucester, if you're still stuck let me know. With your set up you should be making well over 400 bhp, I have the baby 4ltr and running the C30 blower flat out at the top end and that makes good power with no engine mods.

As hoofa says, dump the recirc hose and the box behind the blower, you can do this beac use you are running the Omex 710 and presumably using a MAP sensor for load. The box behind the blower is only necessary when running the lucas 14CUX / AFM where all of the air passing through the AFM needs to be accounted for. Once you go MAP for load the ECU wont give a **** if you're dumping boost to atmosphere.

Here's the part I fitted, it tidies up the whole installation by de-cluttering.

http://www.atpturbo.com/mm5/merchant.mvc?Screen=PR...

fits perfect!

Out of interest, what did you do with the air dumped on closed throttle if not recirculating it? Is it not deafening when it dumps?

[Engineer1949]

Any updates on this problem following with interest


John

[Richard 858]

+1 on interest in an update, especially as I've now had mine tested. With the same charger & engine set up, but still on the 14CUX, Bosch injectors, standard fuel pump but switched back to stock B7 plugs I am running 6 psi of boost, however I was & still am experiencing some belt slip at 5,000 (ish) engine rpm. My numpty comment earlier in the thread about dump valve spring should be ignored