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Jake Lathams C5 ST2 Monster: and indepth look at some details
Now that the Season has come to an end, I wanted to take the time to detail out the extensive work we did on Jake Lathams C5 in the months leading up to the NASA championships.
Jake took home the NASA National championship in both ST2, and TT2. It was no walk in the park, as the win margins were slim in both classes.
We took the same approach we usually take on these cars, which is as light as possible and then let the power end up where it has to.
These modifications include, but not limited to:
Install Flat floor to gain overall downforce (Manufactured by Zebulon Motorsports)
Belly pan fabrication to connect floor to front undertray
Diffuser install to connect rear of floor to exit of chassis
Side exit headers
It was determined that the center OE style exhaust would not play well being enclosed, even with cooling vents
We had already planned for side exit headers when we built this car originally 2 years ago, but the plan and execution are sometimes not the same, LOL.
The drysump tank was already located in the trunk
There were no accessories in the area that the header would now occupy
Cutting of the frame rails to make room for mufflers
Multiple muffler configurations necessary as the Championship race was at Laguna Seca
Removal of AJ Hartman/C5R front undertray
Removal of Dewitts radiator and standalone oil cooler
Install of ron davis radiator with integrated oil cooler, we will add 2 additional coolers later down the road for high altitude and an 600whp LS7
Remove normal headers and exhaust
Install of Zebulon front undertray, in a quick release fashion. Why? It would not fit in the trailer with the splitter on. LOL.
GSpeed penske dampers
Check and setup packer gap, and bump stop setup. Why? If the aero loads were high, we want to keep the platform at the min rideheight we are comfortable with. Also, did not want to scrape the belly pan, or induce a choke flow scenario.
Lets get to work! Follow along for all the pics and explanations. Im sure given the indepth of this post and the changes made, there will be some updates 😉 The Final product at Laguna
Burns stainless collectors were used.
OG C5R undertray from AJ Hartman. We have used this style of undertray for almost 20 years.
Zebulon Motorsport flat floor and Radical Diffuser. Jake owned the diffuser, so we used it. Its a solid option, and has no flow attachment issues.
The start of mocking up the floor.
Looking back at the undertray
early layout with Zebulon rockers. These rockers were trimmed for another application, the proper rockers will be installed later
We made a custom cradle to house the radiator independent of the undertray, so that the nose and undertray could be removed with in a minute to load and unload, as it the front splitter would no longer fit in the trailer, lol.
Undertray mocked up
Floor mock up. The composite work was so well executed, you can see the reflection of the stuff underneath it.
Diffuser mount to rear cradle
Cradle and initial mock up of undertray
front splitter/undertray mounted with Jake standing on it.
Starting to cut the rockers for the side exit headers
We know where the exit of the header will be, so we start there and lock and many known "constants" down as possible. This allows the mind to focus on the things that we can control.
Initial set up of the secondary primary into the final merge collector.
Header primary first go, all tacked up.
Bench welding and back purging.
More bench welding and back purging. We used an old cylinder head to bolt the flange to so that it wold stay true.
Belly pan rough in. There is a special undertray support structure bolted to the cradle
full under shot of the floor pan of the car, including belly pan.
Close out panels and start of muffler and collector mounts. We use springs and a muffler/collector self caputre method to retain the exhaust that allows it to have a degree of freedom and not crack prematurely.
Cool weld pic. Total time to build the entire header, muffler, mount and exhaust system, with design included, was 100 man hours.
Passenger side mock up taking shape.
Cutting and shaping of the inner structure once we removed the frame sectin to fit the muffler.
Inside of header tube, back purged weld with good pen. So pretty shot of front end fully assembled with radiator exit duct Drivers side header fuilly welded and installed.
The increased aero required a damper we knew. We moved to our penske double setup that we use on many race winning and championship winning corvettes. While we out of time to re-valve them, we used a shelf damper we had in stock, and adjusted them to the cars needs. We had about 15% of range left at the end of testing. Passenger side header complete and installed. Notice we use a Indycar pressure can for the cooling header tank. We run beteween 30 and 40 psi of coolant pressure to keep cavitation and boil over at bay.
Post race!
Yep, thats a catalytic converter. Just doing what we could with what we had to meet sound.
We added a second battery for the National Championship race. The car will run for 30 minutes in PDM Saver mode with these 2 batteries and no alternator.
Diffuser mounted, and jack point welded on. Since the car is all carbon underneath, there is NO way to jack the car up otherwise.
Testing testing testing.
Setup changes during testing.
Last day of prep before load up.
Radiator inlet duct.
Dyno time
Nose box removed for loading and travel. Removal of this takes about 2 minues. Reinstall takes about 5. no tools required.
Muffler configuration as sent to laguna. this is a 24" bullet muffler with a Metal matrix catalytic converter. We did not trip sound.
Weight plate
Loaded! youll notice that the OG Sledgehammer in the trailer too. we sent the entire car along for spares since it no longer runs in NASA.
Dyno sheet. 320whp of fury. The engine combo is a cam only crate LS3 with a big drysump and light accessories. It makes 470 whp full tune up.
Pre grid at Laguna
Jake and great lakes nasa customer, Joe Kellerman on grid. Joe won TT1, but decided to withdraw as he had a weight issue that wasnt caught by tech.
2014 NASA Texas TT1 Champion
2015 NASA Texas ST1 Champion
2018 NASA TTU & TT3 National Champions
2019 NASA ST2 National Champion
2019 NASA Texas TT2 Champion
2020 SCCA Majors COTA GT2 pole sitter
2020 SCCA Trans Am Road Atlanta SGT Winner
2022 NASA National Champion ST2
2023 NASA National Champion ST2
2023 NASA National Champion TT2
Probably one of the best posts I have seen. Lots of detail plus explanations of the rationale for each change. Superb build. Thank you for putting in the effort to educate the rest of us.
Great lakes nasa customer, Joe Kellerman on grid. Joe won TT1, but decided to withdraw as he had a weight issue that wasnt caught
I was trying to compete in TT1 but had brake issue.
My understanding is Joe would have won TT1 but refused to get dyno'd. He had staggered tires in the rear and said the dyno runs would ruin his differential.
Last edited by slow04cobra; 11-21-2022 at 06:10 PM.
I wish i didn't have braking issue, i had nothing for Joe. On friday to set the grid for Saturday's session they both went flying past me. I knew i had no chance of keeping up.
Great lakes nasa customer, Joe Kellerman on grid. Joe won TT1, but decided to withdraw as he had a weight issue that wasnt caught
I was trying to compete in TT1 but had brake issue.
My understanding is Joe would have won TT1 but refused to get dyno'd. He had staggered tires in the rear and said the dyno runs would ruin his differential.
I think you are right. Either way, it was a voluntary withdrawing.
11-19-2022, 10:15 AM
Jake Lathams C5 ST2 Monster: and indepth look at some details
