dyno tune or not?

grumpyvette

grumpyvette

Administrator
Staff member
MARTY said:
I have what was originally a 1970 454 corvette, now with a dual quad holley carb, high compression 468 big block combo. It seems like it runs decently and while it runs about as expected, I get less than 12 MPG, and I have a feeling I could get a bit more from the engine "as IM sure most guys do".
I know it's hardly ideal as an economy car but I get the feeling I could be getting, or get better gas mileage. I'm thinking about taking it in and having a dyno tune done, since I don't really know as much as Id like to about tuning dual quads or setting the timing, jets etc.
could you give me some idea as to the cost and time required?
I talked to a local speed shop that has a dyno and they say $120/hour, and it should take them 4-5 hours, to me that sounds rather high? .
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Yes its an experience that may be rather useful, and youll certainly learn a few things about your car if the guys doing the work will allow you to watch and ask questions and if you understand whats being checked and adjusted, but as in most things the knowledge and experience of the guys doing the work has a huge effect on results and your always likely to find guys who are not willing to do much more than the minimal corrections required to show some basic improvements rather than go into the adjustments and corrections required to allow the engine to reach its true potential. after all swapping jets or verifying the result of changes takes some time and effort and theres a strong tendency to have guys doing the work call it "GOOD ENOUGH" or the owner of the car to not want to pay for the required dyno time, but theres also a tendency in some shops to try to maximize profits by extending the time it takes too!
ok, a few facts , youll obviously want to look around your area and find out where there even is a dyno testing facility that allows you to put the car on what effectively is a treadmill for cars and one thats set up to handle the potential power levels you could reasonably expect to see your car produce.
THEN, it makes a good deal of sense to ask for references

Ive had this done only a few times because even though I don,t have a dyno, I found that if you know how to tune, can read spark plugs well, have a quality IR temp gun and have a fuel/air meter and exhaust gas analyzer , (all of those tools combined are likely to cost less than the $600 your quoting) IF you learn the basics of what to look for and how injection, testing sensors, carbs,power valves, jets,boosters,accelerator cams, jetting and setting up a fuel system, etc. you can do a remarkably good job yourself .
on the few times I have had guys dyno engines Ive built we found that there were minimal gains to be had and what they got was mainly confirmation that the car engine put out significant power, but its rarely as much as the owner likes, because rear wheel horse power measured on a dyno is rather consistently 17%-20% less than the dyno numbers posted in magazine articles from engines run on engine dynos, so don,t be surprised if a engine you are dead sure makes in excess of 500 flywheel hp shows closer to 400 on a rear wheel dyno test.

related threads, yeah its a great deal of links, but worth the effort, to follow thru.

viewtopic.php?f=69&t=3175&p=8459&hilit=dyno+tune#p8459

http://garage.grumpysperformance.com/index.php?threads/verifying-your-real-advance-curve.4683/

viewtopic.php?f=55&t=6765

viewtopic.php?f=55&t=211

viewtopic.php?f=55&t=1790

viewtopic.php?f=69&t=8540&p=29972&hilit=dyno+tune#p29972

viewtopic.php?f=69&t=5074&p=14421&hilit=dyno+tune#p14421

viewtopic.php?f=69&t=3375&p=9224&hilit=dyno+tune#p9224

viewtopic.php?f=69&t=3175&p=8459&hilit=dyno+tune#p8459

viewtopic.php?f=55&t=1200

viewtopic.php?f=55&t=635

viewtopic.php?f=55&t=5229

viewtopic.php?f=55&t=1639

viewtopic.php?f=55&t=109

viewtopic.php?f=55&t=7763

viewtopic.php?f=55&t=8126

viewtopic.php?f=55&t=1144

viewtopic.php?f=70&t=202

viewtopic.php?f=70&t=2798

viewtopic.php?f=70&t=4683

viewtopic.php?f=70&t=3949

viewtopic.php?f=55&t=3522&p=9307&hilit=exhaust+gas+analyzer#p9307
 
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keep in mind a dyno tune is by design rather stressful on your car as it will be pushed to near its power limits at least briefly and the object is to adjust and correct things that are NOT correctly adjusted while doing so!
most american V8 engines will run best with a fuel air ratio close to 13.8:1 at idle and slowly transitioning to a fuel air ratio closer to 12.6:1 by about 3500 rpm and higher this tends to prevent the plugs fouling and reduces the chances of detonation.
spark plug gaps set at around .045 and running a 180F t-stat and a low restriction oil filter, clean,new 10w30 synthetic oil and while your there ask questions and take notes and be darn sure that your engines already in decent tune, your going to be paying an hourly fee, you don,t want to pay some guy to be giving the car a basic tune-up at $70-$200 and HOUR.
ID expect you have already CORRECTLY adjusted your valves and ALREADY done a compression check and written down the results, and VERIFIED TDC and installed a marked damper,or at least timing tape ,PRIOR to arriving at the dyno test station
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http://www.thedynoshop.com/pages/whatisDT.htm

http://rttuning.com/services/dyno-tuning-2/

http://www.onpointdyno.com/?page_id=2254

http://www.onpointdyno.com/blog/wp-content/uploads/2012/12/PreDynoChecklist.pdf

http://www.vip-performance.com/DynoCheck.html

http://www.hotrod.com/how-to/engine/hrdp-0607-performance-engine-dyno-testing/
 
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Better off going to the local 1/8 mile or 1/4 mile dragstrip I say Grumpy.
Real proof is timeslips.

Lots of backroads around me to test and tune on.

$120-$200 bucks an hour.....
Tune myself Thank You.
 
$120-$200 bucks an hour.....
Tune myself Thank You.
Click to expand...

yeah! in fact one of the last times one of the neighbors kids had his car dyno tuned, a few weeks earlier we had done a tune up and adjustments on the kids 1969 440 road runner engine and the net improvement after the dyno tune was 6 hp and if you know anything about setting up and running a dyno, simply changing a few test setting's could easily compensate for that variation.
So simply having your car dyno tuned is not a set in concrete guarantee that youll see a huge jump in power
 
Grumpy said:
yeah! in fact one of the last times one of the neighbors kids had his car dyno tuned, a few weeks earlier we had done a tune up and adjustments on the kids 1969 440 road runner engine and the net improvement after the dyno tune was 6 hp and if you know anything about setting up and running a dyno, simply changing a few test setting's could easily compensate for that variation.
So simply having your car dyno tuned is not a set in concrete guarantee that youll see a huge jump in power
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They have thier uses Grumpy.
From what I have seen 5.0 racecars in the past.
Supercharged 1400+ HP. 8-Seconds.

I don't have the $ to go that fast.
Only a few remain outof Eds old group.
They are low on $ too.

Bam Bam.
 
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