asoduk
asoduk New Reader
May 12, 2013 10:25 a.m.

Yesterday the local Porsche club had a "dyno day" at a new shop in the area. Anyone could come and run their car on their 4 wheel superflo dyno for a pretty reasonable price. I was really expecting a lot less than what they had....

Their shop used to be a strip mall full of offices. It is now a huge L-shaped speed shop. Their lobby/waiting room had a Maserati Gran Tourismo Stradale parked in the middle with nice leather couches, TVs, refreshments, and some wheels on display. In the next office suite: cars waiting to get work done or be picked up. The coolest of which was an E30 widebody with a turbo LS3. Moving on to their garages: 350Z with an LS swap, an old Nascar, some Mustangs and BMWs. Pretty slick, picture links coming soon....

So then I got to run my spec miata on their dyno. It was LOUD. I put down an earth shattering 99.9 RWHP. They also ran an A/F sensor in the exhaust and found my car to be quite lean (15-16.5 before I blew the sensor out). Despite the fact that I've been running it that way for years now, I'm a little concerned and would like to get those readings to be more healthy.

The car is a '91 1.6 with the usual SM "intake" and a springfield dyno exhaust. The bottom end has never been touched.

So what does the braintrust here (paging Keith Tanner) suggest for getting my A/F numbers more in check. My immediate thought is going to the adjustable fuel pressure regulator that is now allowed in SM.

Swank Force One MegaDork
May 12, 2013 10:38 a.m.

The "sniffers" on the dynos oftentimes aren't real accurate. If you have exhaust leaks before the sensor, then the reading won't be accurate, either.

If you're willing to spend a little money tracking this down, i'd suggest buying a wideband of your own and checking for yourself.

May 12, 2013 11:32 a.m.
Swank Force One wrote: The "sniffers" on the dynos oftentimes aren't real accurate. If you have exhaust leaks before the sensor, then the reading won't be accurate, either. If you're willing to spend a little money tracking this down, i'd suggest buying a wideband of your own and checking for yourself.

this

racerfink SuperDork
May 12, 2013 6:54 p.m.

My bone stock SM motor with 196k miles and Springfield Dyno exhaust made 112.8 rwhp. What kind of intake are you running? I have a tube from AutoTechnik with an AutoZone air cleaner.

asoduk
asoduk New Reader
May 12, 2013 8:53 p.m.

Thanks for the input guys. Sounds like I'm going to be buying a wideband AND an adjustable FPR.

As for the result, this was done on a Superflow AutoDyn - 880E AWD Dynamometer. They read lower than Mustangs or DynoJets, which is what most people are more familiar with. Everyone had much lower numbers than they had before. I was actually expecting a little lower. I'm normally around 115 on a DynoJet (without sniffer).

So, any suggestions on what to buy? preferably something that won't kill my tire and brake budget.

amg_rx7 Dork
May 12, 2013 9:13 p.m.

Similar thing happened to me. Replaced the original fuel pump and replaced the "tuned" air flow meter w/ a stock one to fix the problem.

Dynos can be quite accurate if the operator knows what they are doing and it is maintained. If it is a newly installed dyno at a high end shop, it is probably accurate.

Is the air flow meter stock / unmodified? A "tuned" AFM can result in a leaner mixture.

What kind of fuel pressure is the car producing? A tired old fuel pump will not keep up with the motor's demands and result in lean AFR.

Suggest you look at that before spending $$ on go fast parts.

I'd also suggest doing a compression check and a leak down test to see what the overall health of the motor is.

beans New Reader
May 13, 2013 8:32 a.m.

My '95 1.8L with an RB intake, 2.5" steel crossover tube, homemade heat shield, and Borla exhaust made 119whp on Pure Tuning's dyno about... 6-7 years ago? I was pretty surprised for a near stock DD miata. Stock clutch/flywheel, 4.10 Torsen rear, 35lb wheel/tire combo. Pure does a lot of SM dynoing, they said mine would've been on the strong end for SM cars. I have a dyno sheet floating around somewhere, but the sucker wanted to pull past rev limiter pretty good. Was a quick car in the 1/4 too, ran a 15.6@89mph at Milan dragway.

asoduk
asoduk New Reader
May 14, 2013 8:42 p.m.

Thanks guys. Some good info and things to look at. I'm going to start with a wideband and then cheap parts, including my stock (non tuned) AFM.

You'll need to log in to post.

Also on Grassroots Motorsports

Tonight on Grassroots Motorsports LIVE! Lee Grimes of Koni Shocks

4 hours ago in News

This may shock you, but suspension is arguably the most important part of going fast.

Classic Motorsports Monterey Welcome Party Welcomes 2000-Plus Gearheads

11 hours ago in Articles

Last night we threw a party, and more than 2000 people came to celebrate.

We're Back In Monterey for Car Week

1 day ago in News

And so it begins, another trip to Monterey Car Week.

Deal of the Month: Free Trackside Companion!

1 day ago in News

Ever wished you had a handy guide on how to dial in your alignment or adjust your dampers?

This Tuesday: Join Us at Track Night in America

2 days ago in News

This Tuesday we'll be running at Palm Beach International Raceway

Experience Monterey With Us

2 days ago in News

We're on our way out to Monterey, California, for car week.

Concours d’Lemons to Ruin Monterey Car Week Yet Again

2 days ago in News

What started as the anti-concours has transformed into a major event on the Monterey Car Week schedule.

Tomorrow, August 15: Join our Monterey Kickoff Cruise-In

2 days ago in News

Our Monterey welcome party is taking over all of downtown Pacific Grove.

Vintage Views: Classic Mini

5 days ago in Articles

Turn heads, have jolly good fun.

You Need This: Toyota With Rally Pedigree

5 days ago in News

Who can say no to a turbocharger and all-wheel drive?

Join Our Monterey Kickoff Cruise-In at Pacific Grove on Tuesday, August 15

5 days ago in News

Our Monterey welcome party is taking over all of downtown Pacific Grove.

You Need This: J. Geils's Maserati Sebring, Some Assembly Required

6 days ago in News

A rock star project will be auctioned off in Monterey next week.

OUR SPONSORS

Grassroots Motorsports Magazine

Subscribe Today

Also get your instant access to the digital edition of Grassroots Motorsports Magazine!

Learn More
VhrGbqMmCmUZ4v1iEW7fatDmteH2LuVZ