wxywb021254 Posted January 23, 2022 Share Posted January 23, 2022 (edited) Hi 7 owners. I did a Dyno run today for my 420s. Got 141 whp and 120 wtq. Seems low to me although I cannot find any other Dyno online. Wondering if it sounds normal. Car runs fine except in winter, cold start is tricky. For Dyno, it was a dynopack Dyno and the pulls were done in 4th gear. Diff ratio seems to be set to 3.98 although I don't know if it matters. If troubleshoot, where do you suggest to start? Did a compression test on a semi cooled engine. Cylinder 1-4 have 215, 210, 220, 215 psi. No idea a normal value for 420 duratec though. Thanks! Edited January 23, 2022 by wxywb021254 Link to comment Share on other sites More sharing options...
Croc Posted January 23, 2022 Share Posted January 23, 2022 Dyno results are always controversial. The 420 has a claimed 210hp at the flywheel. Caterham claims are sometimes "flexible" so that may be a factor here. Allow for 20-30% drive train loss is my usual consideration. Fuel octane used does influence the result. There is ALWAYS considerable variance based on the type of dyno, technician using it, etc. While yours is on the low end of what I would expect, it is within a range I would expect. Cylinder reading is where I would expect - I dont think your issue there. If you want to unlock hp the best way is to get it properly dyno tuned. The Caterham locked ECU tunes are very conservative and overly rich. That is expensive since you have to do a remote tune with SBD UK or buy a new unlocked ECU to have someone in the US do the tune but it works everytime - probably at least 20 more hp, better torque curve and a smoother engine response feel. @simon450 @sf4018 @SK400 Random ping as you are the only 3 I know who may have dyno'ed your 420's (before upgrades) so may have a dyno plot to answer this question. Link to comment Share on other sites More sharing options...
SK400 Posted January 23, 2022 Share Posted January 23, 2022 Something seems off. What gearbox do you have if I may ask? Typically, peak horsepower for the r420 cams is at 7,100 rpm, so surprised the peak on the graph seems to be before 7,000. i did not dyno my car before adding roller barrels unfortunately but with the roller barrels, 6 speed gearbox, and the Caterham ECU, my car dynoed at 198 hp or roughly 200 hp at the wheels. The roller barrels made a difference but not more than 10 or 15 hp (felt it at top end). i ll try to find an old post on this forum where I had included a few dyno charts. Link to comment Share on other sites More sharing options...
SK400 Posted January 23, 2022 Share Posted January 23, 2022 Link to comment Share on other sites More sharing options...
wxywb021254 Posted January 23, 2022 Author Share Posted January 23, 2022 Thanks @Croc. 20-30% loss seems high but I get your point. Yes, cylinders seems fine to me also. Plan to swap spark plugs. They were original Ford plugs and plan to change to br7efs. thanks @SK400. My car has the 5 speed transmission and bmw LSD. I was also wondering about the peak power rpm but except an online crank Dyno curve, I didn't see any other Dyno plot so not sure... Don't tell me Caterham may have the wrong cam in the car🤣 Link to comment Share on other sites More sharing options...
Sean Posted January 23, 2022 Share Posted January 23, 2022 For reference, various drivetrain loss values for 141 whp: 15% -- 165.9 20% -- 176.3 25% -- 188.0 30% -- 201.4 Link to comment Share on other sites More sharing options...
sf4018 Posted January 24, 2022 Share Posted January 24, 2022 I got 204HP after 15% add on for drivetrain loss. It was tuned quite rich, focus was response and reliability rather than outright HP, so there’s no doubt more in there. 141HP does seem off. Link to comment Share on other sites More sharing options...
wxywb021254 Posted January 24, 2022 Author Share Posted January 24, 2022 29 minutes ago, sf4018 said: I got 204HP after 15% add on for drivetrain loss. It was tuned quite rich, focus was response and reliability rather than outright HP, so there’s no doubt more in there. 141HP does seem off. May I know what kind of Dyno did you use? I am thinking to use another Dyno to verify now... Thanks. Link to comment Share on other sites More sharing options...
sf4018 Posted January 24, 2022 Share Posted January 24, 2022 5 minutes ago, wxywb021254 said: May I know what kind of Dyno did you use? I am thinking to use another Dyno to verify now... Thanks. It was an inertia roller, can’t remember the brand, but it wasn’t fancy. Link to comment Share on other sites More sharing options...
wxywb021254 Posted January 24, 2022 Author Share Posted January 24, 2022 1 hour ago, sf4018 said: It was an inertia roller, can’t remember the brand, but it wasn’t fancy. Hello @sf4018, thanks for the information! I am wondering if the dyno is the reason. Will try with some other type of dynos. Thanks! Link to comment Share on other sites More sharing options...
fastg Posted January 24, 2022 Share Posted January 24, 2022 I would not start chasing dyno number, it's pointless. A Dynopack Dyno is a good setup, I think it's a hub dyno so it removes the tire drum interface. If the shop is convenient and the staff responsive keep using them. The numbers are for your reference so you can compare changes. Or you can go chase numbers, slip the dyno operator $50, he will pump the tires up good and hard, play with the temp and pressure setting, you will get some good numbers. But guess what the actual HP the engine produces will not change. Graham Link to comment Share on other sites More sharing options...
JohnCh Posted January 24, 2022 Share Posted January 24, 2022 I'd call the shop and ask what percent loss they normally see on stock engines that come through their shop. If they do any volume, they should have a guestimate based on experience and that will give you an idea if the number is wildly off or in the ballpark. The thing that surprised me is the big torque dip around 5k. Assuming that's not exaggerated by scaling issues, does anyone know if that is normal in the 420 without roller barrels? Looking at the curve for my old engine that has the same cams as the 420 but Jenvey throttle bodies and a different exhaust (4-2-1 with very long secondaries), it's pretty flat with the torque peak much higher in the rpm range. -John Link to comment Share on other sites More sharing options...
KnifeySpoony Posted January 24, 2022 Share Posted January 24, 2022 Agree, something is off. Torque curve shouldn't look like that on a 420 I don't think. Mine is just starting to pull at 5k. Link to comment Share on other sites More sharing options...
wxywb021254 Posted January 25, 2022 Author Share Posted January 25, 2022 Plan to change spark plugs and redo a dyno on a dynojet with AFR. Any other idea on starting point for troubleshooting? The issue here is I don't have any shop who is familiar with Caterhams... Link to comment Share on other sites More sharing options...
sf4018 Posted January 25, 2022 Share Posted January 25, 2022 28 minutes ago, wxywb021254 said: Plan to change spark plugs and redo a dyno on a dynojet with AFR. Any other idea on starting point for troubleshooting? The issue here is I don't have any shop who is familiar with Caterhams... That seems like the lowest hanging fruit, hopefully that gets you enough of the way there. Link to comment Share on other sites More sharing options...
fastg Posted January 25, 2022 Share Posted January 25, 2022 Dyno shops don't really care about the car, it the engine and ECU. The only issue with the car is how to strap it down, but one look under the back will answer that question. For a basic dyno run they just need the engine so they know were to pick up the RPM signal. When I talk to a dyno shop I will say I have a Locost with a K24. Graham Link to comment Share on other sites More sharing options...
wxywb021254 Posted February 16, 2022 Author Share Posted February 16, 2022 (edited) Update changed the spark plugs and went to a dynojet shop for dyno. This time numbers seems much reasonable. 160 who 130 wtq. But the shop is concerned about AFR seems to be very lean at lower rpm. Do you guys see the same? I see @SK400has similar AFR but that’s on roller barrel. Ideas? Thanks. Edited February 16, 2022 by wxywb021254 rotated image Link to comment Share on other sites More sharing options...
fastg Posted February 16, 2022 Share Posted February 16, 2022 You look to be around 14.7:1 AFT, perfect for emissions, not perfect for HP. But I would not call it dangerously lean. I see you found a Dynojet:) Graham Link to comment Share on other sites More sharing options...
JohnCh Posted February 16, 2022 Share Posted February 16, 2022 I've been told by a shop that has tuned a lot of Duratecs on the dyno over the years that max power correlates to AFR in the 12.5:1 - 13.3:1 range and to shoot for 13:1. I agree with Graham that those numbers are not ideal at full throttle but not likely dangerous on a stock 420 engine, particularly given they richen up at high rpm. BTW that torque curve is really, really flat! -John Link to comment Share on other sites More sharing options...
wxywb021254 Posted February 16, 2022 Author Share Posted February 16, 2022 25 minutes ago, fastg said: You look to be around 14.7:1 AFT, perfect for emissions, not perfect for HP. But I would not call it dangerously lean. I see you found a Dynojet:) Graham Yep. I found a dynojet 12 minutes ago, JohnCh said: I've been told by a shop that has tuned a lot of Duratecs on the dyno over the years that max power correlates to AFR in the 12.5:1 - 13.3:1 range and to shoot for 13:1. I agree with Graham that those numbers are not ideal at full throttle but not likely dangerous on a stock 420 engine, particularly given they richen up at high rpm. BTW that torque curve is really, really flat! -John As long as it's safe, I am fine at least for now, I am not too worried about powerrrrrrrrrrrrrr... Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now