Sined7

Had some free time at work the other night so I decided to strap the new ride to the rollers and get a baseline. I will be working on a few performance components such as an intake w/ a velocity stack and test pipes as well as doing a tune using an Apex AFC in the near future.

100% stock 1998 GS400 190,300 miles on the clock ... I'd have to say she's running up to par and stronger as ever.



Run was taken in 3rd gear. Running a little rich on the A/F's. When tuning NA cars I shoot for 13.0-13.3 A/F's so I would have to say that there is a few HP to be gained even on a stock GS by tuning, we'll see shortly

BoostAddct

I look forward to your future mods and tuning. Keep us posted.

GILLEXUS

iTrader: (14)

Hey Sined7,
Do you have a dyno where you can dyno anytime? If so that's great. I lot of us would like to try and test different things but it's hard to get dyno time to test and tune things.

Just a few questions,
1. You mentioned run 3 was in 3rd gear what gear was run 5 the one you posted?
2. What is the condition/mileage on your plugs & air filter? How about doing another base run w/ new plugs if current ones have a lot of miles on them.

Nice base hp #'s

GSteg

iTrader: (15)

I thought 4th gear was the gear to run in since it's a 1.000 ratio?

DarKnight

iTrader: (3)

Sined7

I just purchased the car a few weeks ago and have only address the oil change and suspension (bad ball joints made that #1 priority). Honestly ... I can not tell you the condition of the plugs and the air filter was a bit dirty. I was looking at how the MAS was built, contemplating how I want to build an intake, and I had it in my hands so I bumped and used compressed air to knock out the dirt prior to the dyno.


4th is 1:1 but most NA cars give a better readings in 3rd gear, plus it was later at night and 4th gear runs take longer and I didn’t want to **** the neighbors off. I will make runs w/ future mods in 3rd gear for comparison sake but I will try a 4th/3rd gear comparison next time I have it on the dyno to see which is the better reading gear.

GSteg

iTrader: (15)

you are the man! I can't wait for more results!

GILLEXUS

iTrader: (14)

DUH, Sorry . Gee, what was I reading or not reading

4th gear is ideally the gear to use since like you said the ratio is 1:1. I've used 2 dyno shops one was able do 4th gear but I usually could not good reading untill about 3500+rpm. That shop tried both gears and for me 4th yielded about 5-6 more HP and I think about 8-9 more TQ.
The most recent shop used 3rd because it was esaier to get good full throttle pulls and 4 gear keeps wanting to down shift to 3rd when you acclerate hard to red line.

JBrady

Strong numbers. Are they actual or corrected? If actual, I am guessing it was fairly cool at night in Penn? These engines definitely respond to good air. Even the correction factors get scewed as in hotter air they tend to pull timing quickly. Sensitive retard probably because of the 10.5-1 compression and the knowledge that many will pump regular gas even though it requires premium.

Too bad there was not an easy way to hold these cars in gear to get 2500+rpm pulls.

Looking forward to your tests. Maybe some exhaust work in the future?

Sined7

Yes, it was corrected (SAE). You can see it on the top of the screen shot.

We have had some warmer nights lately. I think it was in the 60's when I did the runs.

Exhaust work is in the near future. I plan on building test pipes 1st, this seems to be something that has not been address on these cars. We will see what the gains will be just from that. I also would like to build an axle back muffler set w/ aluminum tubing and Titanium mufflers. We use aluminum for exhaust on the race cars and I want to see how it will hold up on daily use. Then from there build a true dual w/ X-pipe exhaust system.

jbrady ... a question for you ... what is the collector flange diameter on the S&S headers? I will make the test pipes to accommodate this. I'll have to call them to see if I can purchase a set of flanges, either that or from Lextreme.

o2GS43o

That's quite a bit of miles on a 98'... but she still runs stong i see...

GS FONZy

iTrader: (6)

i tryed buying some from lextreme, but he did not have any. i want to do test pipes as well since i have read that it's possible to gain 5 to 8hp. but some people have mention that the o2 sensors will throw a check light since there is pre and after cats o2. hope you get some flanges and figure out if the engine light thing is true.

JBrady

I have thought about aluminum before. It could work well if you can avoid stress cracking. Reducing weight is always a good goal.

The SS header collector diameter is 2.5". The stock cats entry is closer to 2" and the outlet diameter pipes are just under 2" OD. The SS 2.5" allows the step flange at the cat front edge to fit inside. Not a perfect solution but reasonable considering production costs. I am a believer is small collector volume and would actually prefer a 2" ID collector exit (would also match cat inlets) but this would require multiple additional manufacturing steps adding substantially to cost. With the cats in place the difference is limited. Without cats there may be more of a reduction in low rpm torque and response and drivability. When you make test pipes I would suggest trying both the 2.5" od and then with a 2.25" pipe inserted to create a smaller ID.
Peak numbers may not be effected but part throttle most likely will.

BTW, I think the Lextreme flanges are for the early cars that use a different size 3 bolt flange that is not a bolt up on 98 and newer cars.