LR2: Engine Swap?!

Nicholas Love — Thu, 17 Sep 2020 03:19:48 +0000

LOVERACING

LOVE LEARNING BUILDING RACING WINNING

RACE RECAP

Engine Swap?!
LR2: Texas Strikes Back

We are excited to be one of the first teams in ChampCar to run a Honda K series engine in a B class Miata. We honestly believe this will be a very competitive car in this growing class and we are so excited to see everyone at the track!

INTRODUCTION

INTRO

LR1 started out as a very modest 1.6L Spec Miata to ChampCar conversion. Aero was quickly added, as it was the cheapest way to gain speed. Weight reduction and power were valued less than team strategy and reliability, and that formula worked well. LR1 helped us become the team we are today without having to worry about much else besides driving prowess and fuel strategy. It was the perfect way to start Love Racing. After a year and a half of racing with respectable success, we did the inevitable and swapped in a 1.8L VVT engine to mitigate time lost on the straights. LR1 continues to grow along with the team, but we knew we had the capability to really take things to the next level.
Discussions of a second car became more and more prevalent in our team meetings until, eventually, this idea became the obvious way forward. At the end of 2019, our Texas chapter, consisting of Royce and Jacob, took the plunge and bought a barely running 1999 Miata in “Hard S” trim for $1000, delivered. Say hello to LR2!

GOALS

Before digging into any project, goals need to be outlined. We wanted to apply all of the lessons learned from LR1 to LR2 and were very inspired by the guys over at Rugged Badger Racing. Roy, while not only very helpful, also shares our philosophy on rules interpretations. Like them, we planned to push the current rule-set to the edges in order to give us a competitive advantage.

The original goals for LR2 are as follows:

Weight reduction: If it doesn’t make the car go, turn, or stop it doesn’t need to be on the car.
Maximise the engine within the rules: Fresh rebuild, head work, raise compression, Intake manifold, exhaust manifold, dyno tuning. (Rugged Badger Racing absolutely knocks this out of the park with stock engines that put down up to 150 whp. I feel more than anything this is the secret to their pace)
VPI point diversification: VPI is a “performance investment” and just like monetary investments, the safest and most reliable way to see a return is by diversifying and value per dollar.
Egonomics: Miatas are small, some drivers are big. The car needs to be comfortable for all sizes of drivers.
Cost: Total build cost not to exceed $10,000

ENGINE ANALYSIS

Right out of the box, our engine was trash. At some point in LR2’s hard, neglected, previous life the timing belt was changed and the crank pulley hub was not properly tightened to the nose of the crank. As a result, the keyway in the crank nose was destroyed, which left us with a few options on how to proceed:

Get the crank nose keyway and hub machined to a larger key size. Rebuild engine.
Buy another used Miata engine locally and hope the crank isn’t ruined. Rebuild engine.
Swap in the JDM BP5A engine under rule 4.5.5.1 in the BCCR. This is the same engine Rugged Badger Racing uses. Rebuild engine.
Swap in a larger displacement engine similar to the ECOTEC LE5 and run the car in B class.

ENGINE OPTIONS

Options 1 and 2 would essentially raise our budget by roughly $300-$500 without offering any real advantages, as compared to the others.

Option 3 seemed to be the safe route, proven through Rugged Badger Racing’s experience and success with these engines. The JDM BP5A comes with low miles (due to Japan’s stringent emissions laws), a hotter intake camshaft, and a tubular exhaust manifold without a VPI increase. The downside is that this option is very expensive, $1500 + freight shipping, and would still require a rebuild, head work, and an aftermarket intake manifold. This would get us to competitive power levels (~145 whp), but can cost up to $2,000.

Option 4 was tossed around in team meetings for quite a while. We loved the potential the Ecotec platform offered, but historically, teams running this engine did not fare well with regards to reliability. Multiple anecdotes of engine failures are found both in the paddock as well as the online forums.

METRICS & ANALYSIS

To provide some clarity on our pending decisions, we decided to take a first principles approach to this problem. We asked ourselves which power plant would offer the best balance of power, VPI points, cost, availability, and reliability.

To start, we decided to dive deeper into the rules. First, we plotted the VPI point increase for engine swaps at different power levels (Chart 1). We then plotted horsepower/VPI increase against horsepower to attempt to find the “sweet spot” of rated power per VPI points. (Figure 1). This will show the power level where you start to see diminishing returns of power increase per VPI point increase. To plot these, we took the swap formula equation in rule 4.5.2 of the BCCR (Equation 1) and plotted it against discrete steps in horsepower. The HP/VPI Increase parameter will be used in this study along with other non-dimensional parameters to select an engine for LR2.

The “weight” variable here is from the engine swap calculator, which assumes 2153 lbs for 1989-2005 Miatas. Figure 1 offered some pretty interesting insights! It would seem that the architect of the swap calculator was targeting 150 hp (rated) as the target for engine swaps. After this peak there is a sharp drop off in value per VPI point. Interesting to note that the Rugged Badger Racing team is targeting close to 150 whp which equates to roughly 175 hp at the crank (rated). 150 whp also happens to be just about the limit of what is possible with the Miata BP engines within the rules. I would say that the swap rules are well written here and that there is not a significant advantage in swapping in an engine that has a rated power of less than 150 hp. With that being said, the search for an engine began.

ECOTEC

The obvious first contender was the Ecotec series of engines, specifically the 2.4L LE5. These were used on a plethora of different GM vehicles from 2006-2012 (Chart 2) which makes the LE5 the most commonly available and cheapest trim of the Ecotec engines.

As you can see, these make fantastic power figures. However, the swap calculator pretty much prices out anything over 170 hp for the Miata chassis, as seen in Chart 1. With the second gen Miata starting at 350 VPI points and our previously mentioned goal of VPI diversification, anything over 100 points is a non-starter for us. In this study we will use data from the 2006-2008 Buick Lacrosse. This is the LE5 with the lowest rated power at 168 hp and an 83 VPI point increase to do the swap (Chart 1). The LE5 can be found in good condition on eBay for around $850 plus shipping. It was far less common than we thought considering the number of vehicles it came in, but it may be more available in local junkyards.

As stated before, these engines didn’t have a great history of running in ChampCar. So We continued to look for suitable alternatives.

HONDA K24

The Honda K24 series of engines has been a very popular platform for the last ten years. One particular trim of the K24 that stuck out to us was the K24A, specifically the K24A4 (Chart 3).

At 160 hp the K24A4 nearly hits the sweet spot in VPI value per horsepower at 59 points while keeping similar torque to the Ecotec options. This allows for better VPI diversification by freeing up points for other uses. These engines are also quite a bit cheaper than the LE5, at around $600 at local junkyards and eBay. Honda K-series engines are all based around the same architecture with differences in head porting, VVT, stroke, compression ratios, and intake manifolds. Unfortunately, there is no data on the reliability of this engine in ChampCar.

RESULTS & CALCULATIONS

RESULTS & CALCS

Based on the aforementioned constraints, requirements, and metrics, we narrowed our considerations down to three real engine platforms. Please note that, for the remainder of this study, we will assume an actual vehicle weight of 2000 lbs, as opposed to the overestimated number of 2153 lbs used in the swap calculator.

JDM BP5A with headwork, raised CR, and aftermarket intake and exhaust manifolds
- Potential WHP: ~ 148
- Initial cost: $3,500 ($1,500 + Shipping for engine, ~$2,000 for rebuild, machine work.)
- Replacement cost: $3,500
- VPI increase: 50 (Intake and Exhaust manifold at 25 points each)
- Weight/Power ratio: 13.5

LE5 Ecotec
- Potential WHP: ~ 168 (with aftermarket ECU tuning)
- Initial cost: $3,350 ($850 + $2,500 maximum allowed swap cost per BCCR)
- Replacement cost: $850
- VPI increase: 83
- Weight/Power ratio: 11.9

K24A4
- Potential WHP: ~ 160
- Initial cost: $3,095 ($595 + $2500 maximum allowed swap cost per BCCR)
- Replacement cost: $595
- VPI increase: 59
- Weight/Power ratio: 12.5

We then plotted hypothetical engine replacement costs over time in order to get a better picture of what it would cost to run each engine platform over the life of the chassis (FIgure 2).

Now we needed a way to see the big picture. In order to do that we normalized the weight/power ratio of each engine with the HP/VPI Increase parameter found earlier. We then added a factor that considered the total engine replacement cost at “Replacement 3” on Figure 2. This left us with three non-dimensional weighted parameters, in which a larger number equals more value to the team. The values of these parameters were then added together to give a final score. The result of this is seen in Chart 4, while the equations used are seen in Equations 2 and 3.

Some interesting conclusions can be drawn. The JDM BP5A is the clear winner in the HP/VPI Increase parameter because it only costs 50 VPI points to get to its power level. It once again wins when the weight/power ratio is thrown in the mix. When cost is considered, however, the K24 comes out on top. As you can see, the K24’s cost advantage overcomes any shortcomings in the other two parameters, making it the most valuable choice for LR2 and the team.

CONCLUSION

Going back to the original goals that were set for LR2, we find that the reasoning in this analysis is sound and it aligns with goals 2, 3, and 5, mentioned initially:

Goal 2. Maximise the engine within the rules: Swapping in a K24A4 adds around 15 hp and almost 40 ft*lbs of torque while keeping stock engine reliability and staying well within the engine swap rules.

*One thing that was not accounted for in this analysis was the large torque increase the 2.4L engines have over the stock 1.8L. For the same RPM this accounts for much more power under the curve and therefore acceleration. This unfortunately cannot be measured for the lack of dyno charts on stock Accords, Elements, and Odysseys that utilize this engine.

Goal 3. VPI point diversification: With an excellent score in the HP/VPI Increase metric, we have more VPI points to spend on aerodynamics and suspension while remaining in B class.

Goal 5. Cost: Initial swap costs are low and are comparable to rebuilding a stock engine to the limit of the rules. Replacement engines are cheap and plentiful.

CHALLENGES

Problem: The K24A4 came out on top, but is it possible to get a running engine in the car for $2,500, as per the rules?

Solution: KMiata just released a budget-minded “Basic Swap Package” that retails for $1,976.00. Unfortunately, the cost of these engines pushes the total cost to just over the $2,500 limit. This is where the resourcefulness of Love Racing comes into play. Chart 5 shows the projected cost to get a running K24A4 into the Miata chassis. By fabricating and/or modifying many of the required parts for this swap, we are able to complete it for well under the $2,500 limit. Fabricated items are tabulated as the cost of materials.

- recent -

Post Sources

what do you think?

Comment Below!

LOVERACING

The post LR2: Engine Swap?! appeared first on Love Racing.

BUYING LR#1

Nicholas Love — Tue, 07 Jan 2020 23:30:33 +0000

LOVERACING

LOVE LEARNING BUILDING RACING WINNING

LOVE RACING #1

Buying LR#1

…I finally decided that if I ever wanted to begin wheel to wheel racing I would have to purchase a car myself…

I had many discussions with my friends about starting a race team but getting four or five people together to all put money together to purchase a car proved to be insurmountable. There would be disagreements about what car to buy, whether to buy a race car or build one, what series to race in, where the car would be stored, and so much more.

I finally decided that if I ever wanted to begin wheel to wheel racing I would have to purchase a car myself. After scouring craigslist, racingjunk, and ebay, I came across a clean low mileage 1990 Miata.

This car had less than 90k miles and had been raced in Showroom Spec Miata (SSM) and had completed a ChumpCar race. After a quick test drive, I purchased the car for $6500 and went to rent a U-Haul trailer.

Engine: 1.6L 4-Cylinder
Transmission: Stock 5-Speed
Suspension: Spec Miata Bilstein Coilovers
Differential: Mazdaspeed Limited Slip
Safety: Bolt-in Roll Cage, Kirkey Aluminum Seats
Weight: Estimated 2064lbs by previous owner
Wheels: Spare set of 15×7 Kosei K1s

After owning over 5 Miatas this 1990 was by far the cleanest engine bay I’ve ever had. I knew that working on this would be many times better than my grimy turbo Miata.

Car Development Archives - Love Racing

LR2: Engine Swap?!

LOVERACING

RACE RECAP

Engine Swap?! LR2: Texas Strikes Back

INTRODUCTION

INTRO

GOALS

ENGINE ANALYSIS

ENGINE OPTIONS

METRICS & ANALYSIS

ECOTEC

HONDA K24

RESULTS & CALCULATIONS

RESULTS & CALCS

CONCLUSION

CHALLENGES

- recent -

what do you think?

LOVERACING

RESOURCES & DOWNLOADS

LOVERACING

Downloads

iRacing

Toyota GR86

Formula Vee

Ray FF1600

Mazda MX5 – ND

Mazda MX5 – NC

Ford FR500S

Pontiac Solstice

- recent -

LOVERACING

BUYING LR#1

LOVERACING

LOVE RACING #1

Buying LR#1

- recent -

what do you think?

LOVERACING

Engine Swap?!
LR2: Texas Strikes Back