Hello! Log in or Register   |  Help  |  Donate  |  Buy Shirts See all banner ads | Advertise on TheSamba.com  
TheSamba.com
 
race 1600 engine not making power over 3800rpm
Page: 1, 2  Next
Forum Index -> Performance/Engines/Transmissions Share: Facebook Twitter
Reply to topic
Print View
Quick sort: Show newest posts on top | Show oldest posts on top View previous topic :: View next topic  
Author Message
delamarrr
Samba Member


Joined: August 01, 2018
Posts: 3
Location: SA
delamarrr is offline 

PostPosted: Wed Aug 01, 2018 4:02 am    Post subject: race 1600 engine not making power over 3800rpm Reply with quote

Hi, im hoping someone may be able to help me. I race a formula car with a 1600 engine. Ive just had it fully rebuilt by an engine builder who builds a lot of the 1600 engines for my category of racing.

It has a counterweighted crank, new stock cam, new empi heads (standard valve springs) 1:125 rockers, new bearings throughout, new rings, lightened flywheel and all the usual stuff done to make it a race engine thats allowed.

Ignition timing was set on the dyno and is correct.

My problem is after the rebuild on the dyno it will not make any more HP after 3800rpm. Ive compared it to my other race car which keeps making HP up until about 5000rpm then drops off. The two race cars are about even until 3800rpm. My car runs a motec logger and shows im down about 8kmph on the straight compared to before the rebuild.

It has all the same ancillary bits like fan, carby, manifold ends and fuel pump. My tune is near spot on at about 0.86 across the chart.

It still revs quite happily to my shift point of about 5600rpm

Has anyone got any suggestions as to why it stops making more horsepower above 3800rpm?

Please take into account that our engines in this category are sealed and modifications are not allowed beyond minor things like valve springs, jetting and a few other little things.

Thank you if anyone can help or suggest things to check
Back to top
View user's profile Send private message Classifieds Feedback
Cptn. Calzone
Samba Member


Joined: June 27, 2007
Posts: 1855
Location: S>E>Alabama
Cptn. Calzone is offline 

PostPosted: Wed Aug 01, 2018 4:04 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

check your dist is advancing properly
_________________
71 westfalia
67 912 Porsche Quintilla
67 Single Cab aka my work horse
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
delamarrr
Samba Member


Joined: August 01, 2018
Posts: 3
Location: SA
delamarrr is offline 

PostPosted: Wed Aug 01, 2018 6:01 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

Ill check it again, but it was set on the dyno for max hp. I would love it to be that simple Smile
Back to top
View user's profile Send private message Classifieds Feedback
Glasser
Samba Member


Joined: September 18, 2007
Posts: 1640
Location: Calgary Alberta Canada
Glasser is offline 

PostPosted: Wed Aug 01, 2018 6:05 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

How does it run in the bottom end? Smooth?
I had a very similar thing happen where the engine ran great in the bottom end, try pulling some rpm and engine seemed like it dropped a cylinder around the same rpm. I believe at this Rpm is where the carbs switch over to you main jets circuit.
I pulled my emulsion tubes and found a piece of crud in one of them. Put back together and she was fine.
_________________
Brent
My build up http://www.thesamba.com/vw/forum/viewtopic.php?t=265364&postdays=0&postorder=asc&start=0
Project#2. Neighbors build up. http://www.thesamba.com/vw/forum/viewtopic.php?t=327008
Back to top
View user's profile Send private message Instagram Gallery Classifieds Feedback
Cptn. Calzone
Samba Member


Joined: June 27, 2007
Posts: 1855
Location: S>E>Alabama
Cptn. Calzone is offline 

PostPosted: Wed Aug 01, 2018 6:05 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

Okay then let's look at this from a strictly straight up point of view something is holding that motor back from reaching past 35 it's either got to be carburetion or ignition if it's not overheating it's not a clearance issue and the thing isn't too tight
_________________
71 westfalia
67 912 Porsche Quintilla
67 Single Cab aka my work horse
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
FreeBug
Samba Member


Joined: March 12, 2012
Posts: 4278
Location: deepest, darkest Switzerland
FreeBug is offline 

PostPosted: Wed Aug 01, 2018 6:08 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

Something restricting fuel flow?
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Cptn. Calzone
Samba Member


Joined: June 27, 2007
Posts: 1855
Location: S>E>Alabama
Cptn. Calzone is offline 

PostPosted: Wed Aug 01, 2018 6:29 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

Yes perhaps something in the fuel line or the fuel pump isn't capable of pumping past 35.
_________________
71 westfalia
67 912 Porsche Quintilla
67 Single Cab aka my work horse
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
Alstrup
Samba Member


Joined: July 12, 2007
Posts: 7179
Location: Videbaek Denmark
Alstrup is offline 

PostPosted: Wed Aug 01, 2018 7:41 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

If it ran and pulled as supposed to on the dyno, you first need to focus on what you have touched since then.
Then check fuel supply.
Then ignition.
If all is ok, check cam lift. It may have gone flat
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
mark tucker
Samba Member


Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
mark tucker is offline 

PostPosted: Wed Aug 01, 2018 9:38 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

ditto to alstrip, look for lose fuel line sucken air. or dead dying cam but that should also show up on low end, but it may take a while... jetted to much or not enough will do it as will a colapsed muffler...if your running one. also air cleaner tops too close to the stacks. air jet rong size...but probably fuel delevery issue.
Back to top
View user's profile Send private message Gallery Classifieds Feedback
vwracerdave
Samba Member


Joined: November 11, 2004
Posts: 15279
Location: Deep in the 405
vwracerdave is offline 

PostPosted: Wed Aug 01, 2018 9:49 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

It's the new EMPI cam or the new EMPI heads.
_________________
2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
2010 Sportsman ET Champion - Mid-America Dragway - Arkansas City, KS
1997 Sportsman ET Champion - Thunder Valley Raceway Park - Noble ,OK
Featured in Dec. 2001 HOT VW's Magazine page 63

Watch my racing video's http://www.youtube.com/user/okvwracer/videos
Back to top
View user's profile Send private message Gallery Classifieds Feedback
mark tucker
Samba Member


Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
mark tucker is offline 

PostPosted: Wed Aug 01, 2018 4:37 pm    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

dead valve sppringy thingys can also affect things like this.
Back to top
View user's profile Send private message Gallery Classifieds Feedback
[email protected]
Samba Member


Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
john@aircooled.net is offline 

PostPosted: Wed Aug 01, 2018 4:42 pm    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

First thing I'd check are dead valve springs.
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net
Back to top
View user's profile Send private message Send e-mail Visit poster's website Facebook Gallery Classifieds Feedback
67rustavenger Premium Member
Samba Member


Joined: February 24, 2015
Posts: 9663
Location: Oregon
67rustavenger is offline 

PostPosted: Wed Aug 01, 2018 8:32 pm    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

mark tucker wrote:
also air cleaner tops too close to the stacks. air jet rong size...but probably fuel delevery issue.


This comment just rang a bell in my head.
I have been having issues wit a set of 36's that ran great before. But once I installed a new engine (that failed do to a failed part) and reinstalled the old engine.
I have been having popping issues with correct running.

I just realized that I have put the tall stacks on the 36's. Rather than the shorter Dellorto stacks. That might be my problem.

Thank you for posting this Mark. It got me thinking.
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!
Back to top
View user's profile Send private message Gallery Classifieds Feedback
delamarrr
Samba Member


Joined: August 01, 2018
Posts: 3
Location: SA
delamarrr is offline 

PostPosted: Thu Aug 02, 2018 4:44 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

I dont think anyone that replied actually read my first post besides capt. calzone and glasser.

Cant be fuel, it has a perfect lambda reading right across the rev range.

Why would it be a dead valve spring? The heads are brand new.

Why would it be a dead cam, the cam is brand new.....

It didnt run as it should on the dyno, it stopped making more power at 3800...

capt calzone + glasser: maybe, im in the process of making a new carb up for it so ill try that soon. however my lambda reading is spot on all the way to 5500 on the dyno. I should add that i serviced the carby after the first dyno run and before the second. The problem was still there on the second run. I think its going to be something internal, so its going back to the builder after my race this weekend.
Back to top
View user's profile Send private message Classifieds Feedback
Bugsy61
Samba Member


Joined: March 20, 2011
Posts: 256
Location: Peoria, Illinois
Bugsy61 is offline 

PostPosted: Thu Aug 02, 2018 9:55 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

Cam off one tooth?
Back to top
View user's profile Send private message Classifieds Feedback
Brian_e
Samba Member


Joined: July 28, 2009
Posts: 3227
Location: Rapid City, SD
Brian_e is offline 

PostPosted: Thu Aug 02, 2018 10:18 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

I am with John. Check the valve springs.

Stock springs are OK for 4000rpm on a stock cam. The second you add ratio rockers, ask it to rev higher, more lift, or add heavier valves, you need at least HD single springs.

Just cause they are new doesn't mean they are good or correct.

Brian
Back to top
View user's profile Send private message Visit poster's website Facebook Instagram Gallery Classifieds Feedback
[email protected]
Samba Member


Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
john@aircooled.net is offline 

PostPosted: Thu Aug 02, 2018 10:26 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

because some heads are shipped with $#!^ valve springs. Check them.

The cam could have gone flat too, the most common time for it to happen is during break in, when it's "new".
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net
Back to top
View user's profile Send private message Send e-mail Visit poster's website Facebook Gallery Classifieds Feedback
vwracerdave
Samba Member


Joined: November 11, 2004
Posts: 15279
Location: Deep in the 405
vwracerdave is offline 

PostPosted: Thu Aug 02, 2018 11:10 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

The cam could have been advanced or retarded 1 or 2 degrees when ground and that could make a big difference when dyno'ing a race engine. Just because any part is new DOES NOT mean it is correct. EMPI has been know for shitty quality control, and you are trusting their accuracy.
_________________
2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
2010 Sportsman ET Champion - Mid-America Dragway - Arkansas City, KS
1997 Sportsman ET Champion - Thunder Valley Raceway Park - Noble ,OK
Featured in Dec. 2001 HOT VW's Magazine page 63

Watch my racing video's http://www.youtube.com/user/okvwracer/videos
Back to top
View user's profile Send private message Gallery Classifieds Feedback
chrisflstf
Samba Member


Joined: February 10, 2004
Posts: 3412
Location: San Diego
chrisflstf is offline 

PostPosted: Thu Aug 02, 2018 11:24 am    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

If it was a " dead" spring, would not it make noise or racket, or rough running at higher rpm? Seems you should be able to hear it, if that was the case
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Brian_e
Samba Member


Joined: July 28, 2009
Posts: 3227
Location: Rapid City, SD
Brian_e is offline 

PostPosted: Thu Aug 02, 2018 12:37 pm    Post subject: Re: race 1600 engine not making power over 3800rpm Reply with quote

Nope.

I built an engine that was on the edge of single or dual springs. I used what I thought were decent HD singles shimmed .100" to bind. After one summer of use it started cutting out about 4000rpm. It ran awesome and pulled hard till just over 4000rpm, then it was like someone pulled 2 plug wires.

The owner chased his tail swapping fuel pumps, complete ignition systems, adjusting valves, etc. Everything was tried. I had a hunch, and pulled a spring to find they had less pressure then new stock springs. Almost all of them were shot.

Being you have Empi springs I would be changing them regardless. A dropped valve makes a pretty big mess of nice new parts.

This would be a really good application for Dan's beehive spring kit.

Brian
Back to top
View user's profile Send private message Visit poster's website Facebook Instagram Gallery Classifieds Feedback
Display posts from previous:   
Reply to topic    Forum Index -> Performance/Engines/Transmissions All times are Mountain Standard Time/Pacific Daylight Savings Time
Page: 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

About | Help! | Advertise | Donate | Premium Membership | Privacy/Terms of Use | Contact Us | Site Map
Copyright © 1996-2023, Everett Barnes. All Rights Reserved.
Not affiliated with or sponsored by Volkswagen of America | Forum powered by phpBB
Links to eBay or other vendor sites may be affiliate links where the site receives compensation.