Alfa Pages

RBL · Posted: Thu Feb 16, 2006 10:16 pm Post subject: Dyno results

I finally put my car in for a rolling road tune today.

I have a 1.7 8valve (Dellorto 40s) from a Sprint in my mid-engined Porsche 550 Spyder replica, so after finally getting the carbs sorted I had it Dyno tuned.

Results: 97bhp at 5500rpm at the wheels. The quoted bhp for this engine is 118 so I was dissapointed (especially as I totally rebuilt the engine) but I was told by the tuner that this figure would have been at the flywheel. Does that sound right?

The car is appearing on Channels 5's Fifth Gear in the next series along side a Westfield Lotus 11. When I find out the date I'll post it if anyone's interested.

Rich

Ben_nz · Posted: Fri Feb 17, 2006 6:03 am Post subject:

Horsepower figures are always measured at the flywheel. For your car to be making 97hp at the wheels suggests it would make a little more than 118hp at the flywheel, I think, because drivetrain losses are normally more than that difference (118 - 97 = 21hp = 17.8%). Someone correct me if I'm wrong.

Dynos are all different though, so if you take your car to another dyno (or the same dyno on a day with different air temperature, Alfa in a better mood etc) you'll measure different horsepower. The main use of a dyno is to measure relative power increases, e.g. if you rejet your carburettors, change your exhaust system, put in some race cams etc what improvement do you see on that same dyno, relative to your last measurement?

Interesting that you recorded peak power at 5500rpm (factory specs say it's 6000rpm). How many kms have you put on the motor since it was rebuilt? Are you using any of the Alfa factory exhaust system? How about air intakes?

Oh yeah, and post some pictures of your car! Very Happy

RBL · Posted: Fri Feb 17, 2006 10:02 am Post subject:

Thanks for the feedback Ben.

Here's a link to some pics of my car (there's loads of pics of other Spyders if you looks around the site):

http://www.pbase.com/550joe/lamin

I'm not sure how to post pics directly on the forum but this should give you a good idea.

The engine was re-built with all standard renewable parts, while keeping the existing pistons and cams. It had done 104,ooo miles before the rebuild and I've done 3000 miles since finishing it in June.

I kept the air filter box and use a K&N panel filter. The whole exhaust had to be custom made and the two muffler boxes are 'straight through', so it sounds great without being too loud, but it does pop quite a lot on trailing throttle. (I think the headers are slightly wider than those of a stock exhaust but they used the narrowest tube they had to retain back pressure)

So really other than the exhaust and a change from Webers to Dellortos, it's standard.

My reason for using the dyno was so that that car could be tuned propery, rather than doing it statically, plus over course I wanted to know the bhp! I see what you're saying about using it to make comparisons. I'll make some mods one day, but for now it's loads of fun. The dyno guy said the best improvements would come from some head work and a better cam - he mentioned a 260/265 degree cam?

If you let me know how, I could post some more engine/exhaust pics.

Rich

RBL · Posted: Fri Feb 17, 2006 10:04 am Post subject:

ps. some of the specs on http://www.pbase.com/550joe/lamin are out of date. eg it has disc brakes at the front.

Rees Cees · Posted: Fri Feb 17, 2006 6:45 pm Post subject:

Bellamachinna · Posted: Sat Feb 18, 2006 12:20 am Post subject:

All i can say...

UAUUUUUUUUU!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Great looking car... And uses one of the best engines in the world...

All the best
P.Camilo
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All'interno della mia macchina, vi sedete, tenete sopra e CHIUDETE IN SU...

Ben_nz · Posted: Sat Feb 18, 2006 3:35 am Post subject:

RBL · Posted: Sun Feb 19, 2006 9:08 pm Post subject:

Thanks for the feedback guys - that all sounds good then. I heard Alfa over estimate BHP too - that's obviously unfounded.

Rich

RBL · Posted: Sun Apr 16, 2006 9:05 am Post subject:

It'll be featured on Fifth Gear this Monday (17th April).

Channel 5, 8pm. Should be good, it was the quickest of the two cars(depending on how they edit it - they seemed to like it on the day, but they could slate it for some reason!)

Let me know what you think.

Rich

Sprintervention · Alfasud Joined: 30 Jul 2004 Posts: 60 Location: York

That looks like a serious package full of fun. I'll certainly be watching.

Best wishes
Chris
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1987 Alfa Sprint Veloce

lee16v · Posted: Tue Apr 18, 2006 8:46 am Post subject:

Yep..... saw it Very Happy

That's a great looking car you have there and powered by a great engine!!
Plato looked like he was having fun and they didn't slate it at all...how could they?
Sounded good to, and that's on the box. Bet it sounds even better in the flesh!! Wink

lee16v · Posted: Tue Apr 18, 2006 8:50 am Post subject:

Oh yeh....forgot to say nice tribute with the number plate!

markgp4 · Posted: Tue Apr 18, 2006 10:12 am Post subject:

saw it too,
very nice looking car, and quick as well,
and as lee said it made a great sound, esp on trailing throttle... pop pop bang Very Happy

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make it go faster Smile

johnboy · Posted: Tue Apr 18, 2006 8:23 pm Post subject:

Hi All

great looking car and as mark said,great sound on over run.i liked the number plate too.

regards john
_________________
WODA WE NEED? MORE POWER!!

Alfa gt jtdm blackline
1990 S2 16v veloce sleeping!
2002 ts gtv the wifes now
1997 seadoo gsx 800
1999 freestyle superjet

RBL · Posted: Tue Apr 18, 2006 10:39 pm Post subject:

Thanks guys!, I 'm really proud of it, the program came out brilliantly. (I was the one with the chequered flag if you didn't blink!)

The popping on trailing throttle can get a bit wearing after a while but the sound is great. The 33 number plate is really a coincidence, but looks good and an indicator as to what's under the bonnet. I've had the number on retention for a while, waiting for this project to be finished. I only completed it last summer so this will be the first full year to enjoy it - weather permitting - there's no wet weather gear!

This site has been really helpfull during the build, it would have been hard without it! So thanks to everyone who answered all my questions! There'll be more when I rebuild the engine next year - I'd like an extra 20+hp.

Glad you liked it, now you know what to do with a 33 if unfortunately the rust and electrics get the better of it!
Rich

ak86351 · Guest

so there is future then..

Looks good, nice job..

What are the main costs to create one?
And what is the weight of the 550 replica? Is it much less than the 33 , so you would expect to see difference in acceleration?

RBL · Posted: Wed Apr 19, 2006 9:56 pm Post subject:

The main website is down but this site gives details of costs.
http://www.technic-motorsport.com/M&W%20Site/index.html

The weight is under 700kg, so acceleration should be quicker, though 15" wheels are used with 195/60 tyres which changes the gearing slightly.

Guest · Posted: Fri Jun 02, 2006 11:23 pm Post subject:

At what RPM would peak power be on a 33 green clover leaf Sprint 1500 engine? 5500 or 6000 rpm?

I have one fitted on my M&W Porsche 550 replica.

Ben_nz · Posted: Sat Jun 03, 2006 9:59 am Post subject:

Guest · Posted: Sun Jun 04, 2006 9:21 pm Post subject:

Thanks.