Author Topic: Belly Tank Build Diary  (Read 364950 times)

Mike Brown and 1 Guest are viewing this topic.

Offline Stainless1

  • Administrator
  • Hero Member
  • ***
  • Posts: 8976
  • Robert W. P. "Stainless" Steele
Re: Belly Tank Build Diary
« Reply #675 on: February 06, 2024, 05:01:24 PM »
Mike minor suggestion... upper shock mount might be stronger with a gusset...  :cheers:
Stainless
Red Hat 228.039, 2001, 65ci, Bockscar Lakester #1000 with a little N2O

Online Mike Brown

  • Sr. Member
  • ****
  • Posts: 384
Re: Belly Tank Build Diary
« Reply #676 on: February 06, 2024, 05:27:46 PM »
Mike minor suggestion... upper shock mount might be stronger with a gusset...  :cheers:

You know Woody said the same thing, I guess that I will add a gusset. 

Online Mike Brown

  • Sr. Member
  • ****
  • Posts: 384
Re: Belly Tank Build Diary
« Reply #677 on: February 13, 2024, 11:39:54 AM »
Going forward this shall be known as the Stainless-Woody gusset.

Offline Stainless1

  • Administrator
  • Hero Member
  • ***
  • Posts: 8976
  • Robert W. P. "Stainless" Steele
Re: Belly Tank Build Diary
« Reply #678 on: February 14, 2024, 12:53:30 AM »
Mike, I did my best but failed... trying to resist mentioning I'm familiar with the 'Stainless Woody" but never needed a gusset...  :roll:  :laugh:  :laugh:
 :cheers:
Stainless
Red Hat 228.039, 2001, 65ci, Bockscar Lakester #1000 with a little N2O

Offline salt27

  • Hero Member
  • *****
  • Posts: 1736
Re: Belly Tank Build Diary
« Reply #679 on: February 14, 2024, 03:17:33 AM »
Mike, I did my best but failed... trying to resist mentioning I'm familiar with the 'Stainless Woody" but never needed a gusset...  :roll:  :laugh:  :laugh:
 :cheers:

I'm guessing this is from hands on experience.     :laugh:

Online Mike Brown

  • Sr. Member
  • ****
  • Posts: 384
Re: Belly Tank Build Diary
« Reply #680 on: February 24, 2024, 11:28:54 AM »
I worked with Jerry Magnuson and TRD on a "bypass problem" with Eaton supercharger kits (back in 1997-98).  I found the transition from "spinning blower in vacuum" to "throttle open" would buck and/or stumble the application of throttle.  Jerry's system had a vacuum line controlling the bypass valve, and by installing an .022" restriction in the vacuum line, the "reboost" was ramped in over about 800 milliseconds, which the ECU could handle easily.

When the blower is spinning, and you close the throttle, it acts as a "booster" vacuum pump in addition to the engine capacity.  Reopening the throttle can drive the measured airflow beyond the capability of the ECU (momentarily.)  Using a portable oscilloscope, I was seeing a 5 volt circuit exceed 5.24 volts (where 4.9 volt was the maximum useable signal in the software).

It all reminds me of the "method" needed to test supersonic airplane design.  It is impossible to blow air supersonic with a fan, but if you put a big enough vaccum tank behind it, atmospheric air will easily go supersonic into that big "hole".  A blower in front of a vacuum pump, becomes part of the vacuum tank when you come off the throttle.  Crazy stuff happens when you reopen that throttle.

If yours has that small vacuum line controlling the bypass, you might try a .023" wire welder tip to see if it helps your throttle control.  I don't actually know what your control system is, of course, but thought I could share my ancient history "memory".  We wound up installing that little restrictor in thousands of kits and ended the complaints.

Thank you very much for that suggestion.  My blower bypass valve is no longer controlled by the ECM, I simply plumbed the blower bypass valve dashpot to the intake after the blower.  The other side of the dashpot is vented (through a filter) to atmosphere.  I was contemplating using "bucking" pressure on this side of the dashpot by installing a needle valve that I could adjust to dampen the response of the bypass valve.  An .023" jet will give me a starting point.  I am always amazed by the "been there done that" help that pops up on this forum.

I appreciate the knowledge gained from racers contributing to this forum.  I would like to have some adjustability with the supercharger bypass valve.  Looking for various "jets" to use for this purpose I remembered that I my nitrous system came with a variety of jets.  I have jets from .018" to .062" which will be a useful range.  The next step was to machine a holder for the jets. While measuring the jets I found the "stem" to be approximately 3/16".  I tried them on a 3/16" compression fitting in place of the ferrule and they fit great. 

Online Mike Brown

  • Sr. Member
  • ****
  • Posts: 384
Re: Belly Tank Build Diary
« Reply #681 on: February 24, 2024, 11:29:47 AM »
A photo of the jet installed in the fitting. 

Online Mike Brown

  • Sr. Member
  • ****
  • Posts: 384
Re: Belly Tank Build Diary
« Reply #682 on: February 24, 2024, 11:31:45 AM »
I plumbed the jet holder to the dashpot with short section of braided hose so that the jets would be easy to change at the track.  I will add a foam filter to protect the jet from dirt and debris. 

Online Mike Brown

  • Sr. Member
  • ****
  • Posts: 384
Re: Belly Tank Build Diary
« Reply #683 on: March 01, 2024, 02:47:34 PM »
To protect the restriction jet from debris I covered the jet assembly with a microphone cover typically used on boom style microphones.  The foam cover fit perfectly. 

Online Mike Brown

  • Sr. Member
  • ****
  • Posts: 384
Re: Belly Tank Build Diary
« Reply #684 on: Today at 02:53:21 PM »
We ran the ECTA mile this past weekend in Arkansas.  The new rear suspension with coil springs and adjustable shocks was a handful.  I started with 5 clicks (of 18) from full soft on both compression and rebound.  The car was almost undriveable with so much twisting under acceleration.  I moved up to 10 clicks then 13 and it was better.  The best run was 204+ in the mile, note that I have been 210+ on this track last year.  That was spraying the NOS for the last 1/4 mile for the 204 pass.  The 210 pass was without NOS.  The restriction that I put in blower bypass valve did help, I did not break the tires loose at all after shifting.  I think that it is a traction issue, the 210 run had a tailwind while the 204 run was against a headwind.  The data shows about the same RPM through the traps for both runs, or my clutch is slipping.  I have a couple of inputs left on my data logger so the plan is capture tire speed for the front and rear wheels.  That should help figure this out.  I was almost at the rev limiter (6,500 rpm) on both runs, with 2.48:1 rear gears.  I switched to 2.22:1 rear gears and went slower (199+).  I plan to do some testing at the dragstrip with the original rubber springs.  Going fast is harder than one would think.